Many games adjust the level of a newly recruited character to match that of the lead character, in an attempt to make that character immediately useful. In other situations, it is the responsibility of the player to level them up, usually putting them in dangerous fights but protected by the stronger characters to level quickly. This strategy is known as “[[{{Munchkin}} twinking]]”, "babysitting" or "piggybacking", and is frequently used in online games to get new characters to your level so you can play fairly together.

Some games will give unused party members a fraction of the experience points gained in fights, but many will just [[LetsSplitUpGang force you to use those characters once in a while]] to make sure they don’t get too weak. Games allowing you to switch out characters at any times are appreciated for this reason.

The ability to switch members of your party in battle at any time may have been popularized by ''FinalFantasyX'', although some games predate this usage. ''BreathOfFire'' had this in its first game, only to drop it afterward.

Used to fight the CantCatchUp phenomenon.
A good way to get the MagikarpPower.
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'''Examples:'''
* The ''KnightsOfTheOldRepublic'' series, ''NeverwinterNights2'', and ''MassEffect'' were especially kind in this regard. All characters gained experience equally, regardless of how who you're playing. The player just has a backlog of skill points to use up when they switch a character. This also applies to newly recruited characters, who have all of the skill points they would have had if they'd been with you from the start.
** ''NeverwinterNights'' and its expansions used a variant of this trope. If you leave a party member behind and come back later they will still be at their old level, but talking to them gives you an option to let them "catch up".
** This system may be a Bioware standard; it features in [[SonicTheHedgehog Sonic Chronicles]] as well.
*** MassEffect itself has only one character level for the entire player squad, meaning any characters you decide to use later or haven't used while you gained levels merely need to have their talents chose.
** In some of these games, particularly ''MassEffect'', the other characters are implied to have been with you all along. They talk about events as though they were present at the time, even though they clearly were not - having your entire party around would really have helped in a lot of situations.
** DragonAge : Origins plays this straight: whenever a character joins the party, they will be, at most, one level lower than your main character, who is generally the highest-level character in the party. This means that it's possible to be level 10, bring in a level 9 party member, level up to level 11, kick out said party member, and put them back in the team as a level 10.
* The ''BaldursGate'' series was more standard: characters would join at a level similar to yours, but would gain no experience if you removed them from the party and came back later.
** To be precise, they join at a level similar to '''where you're expected to be''. If you spent a lot of time grinding before getting a particular character, then he'll be behind the rest of your party - although perfectly adequate for the challenges the world is throwing at you.
*''{{Pokemon}} Red/Blue'' had an item that allowed all Pokemon on your team to share in battle XP. Without this item, a Pokemon had to be in the battle to gain experience (which means you put the [[MagikarpPower Magikarp]] first, and then sub him out immediately). But the EXP ALL proved so annoying (''every'' monster gains experience, which means you go through up to ''six separate dialogue boxes'') that a player usually ended up discarding it and powerlevelling Magikarp the old way. Later games have the EXP Share, a holdable item that shares the XP only with the Pokemon holding it; this is much more convenient and players welcomed it.
** With the advent of Double Battles, there's a specific strategy that can allow your pokemon to jump from 1 (the default hatch level in the DS games) to 15 or more in a single battle by using Explosion (which damages all pokemon and faints the user) and Protect or any other move that negates damage. Since your pokemon faints, all the experience from BOTH opponents goes straight to the lower-level mon. Even moreso if you have the Lucky Egg.
** Also in ''Pokemon'', any monsters that you get via in-game trades are the same level as the monster you traded, which is how you could use really good pokemon in the Pika Cup in Pokemon Stadium ([[GuideDangIt good luck with that]]) (This also allowed you to get several illegal trades, like a Level 3 Electrode in the first game). Sadly, between-game trades don't have the same feature. The Global Trade Station from Diamond and Pearl is getting particular anger for the stupidity of some trade requests. Of course, this is hardly Nintendo's fault...
*** However, all traded pokemon get boosted experience anyway, regardless of what level you received them. You still have to switch them, but it makes things faster. There's also a Lucky Egg hold item that increases experience as well, but it's not much better than using the EXP Share.
*In ''ChronoTrigger'', all party members gain experience, but only "in play" characters get tech points; also, a given pair or trio of characters must fight a combat scene together at least once, after all the relevant individual Techs are unlocked, to use a new [[CombinationAttack Combo Tech]].
* ''{{X-Men Legends}}'' did this, because the game would be flat-out impossible if they didn't; there are [[LoadsAndLoadsOfCharacters enough characters]] that it would suck the fun right out if you had to level them all individually, and there are many times when a certain character is needed over others.
** The second game nearly fully averts this though. There are still leak, but only very little, result in inactive character being many levels behind. GuideDangIt for someone who didn't get characters that has might, levitate, bridge building.
* In ''FireEmblem'', characters gain more experience if the enemy's level is higher than theirs. Therefore, a key strategy is to have stronger characters weaken, but not kill, an enemy, then let the weak character get the kill (and the lion's share of the experience). There is usually one character per game that has fantastic growth rates, but requires mucho babysitting to be a useful character.
** ''Path of Radiance'' and ''Radiant Dawn'' have Bonus EXP that is awarded after battle for completing a map quickly, surviving {{NPC}}s and other stuff. You can award it to any of your characters how ever you see fit and even keep it for later.
*** It is worth noting, however, that in ''Radiant Dawn'' Bonus EXP is limited in its uses. Characters who use it to level up will gain exactly three stat increases per level, unless they've already maxed out so many stats that increasing three is impossible. Depending on how many stats the character in question has already capped, using bonus EXP can either be a huge boon or a handicap. Given that most low-level characters wind up much better if you level them the old fashioned way instead of Bonus EXP'ing them to a high level, this isn't a true replacement for babysitting. (None of this applies to ''Path of Radiance'', where Bonus EXP is equally as effective as regular combat EXP.)
* In ''LaPucelle: Tactics'', a way to level up weak allies is to make a combo attack with a high-level character. If the said high-level character has a sufficiently high Speed stat, it will attack first, kill the enemy, and share the experience with as many as three adjacent allies, making it possible for a character to gain dozens of levels by observation.
** The same goes for most other NipponIchi games, particularly stack-attacking in ''{{Disgaea}} 2'', which let you split the experience ten ways.
*** One particular mission in ''Disgaea'' pits you against ten level 75 monsters in a HopelessBossBattle that ends in a BigDamnHeroes moment. The vassals that come to support you are all more than capable of defeating the monsters on their own, but with a bit of luck you can bring in a Warrior or Brawler to steal a killing blow and rack up about ten levels. Subsequent attempts at that mission replace the monsters with a single level 40 Fafnir, which is actually easily doable at that point and is good for power-leveling using combo attacks.
*** An even earlier mission covers the whole area in an invincibility GeoEffect save one square. In ''Disgaea'' you can [[FastballSpecial throw monsters into each other]], which stacks their levels. The monsters in that area can be combined into a single, level 117 monster. Repeat - there is ''one square'' in the whole map that does not have a permanent invincibility effect...
* In ''CityOfHeroes'', a lower-level character can "sidekick" (for heroes) or "lackey" (for villains) to a higher-level character, temporarily becoming the equivalent of one level lower than their mentor as long as they're within 200 yards of the latter. More directly, almost all experience earned by any character on a team will also be gained by each of the team's other members, as long as they're already roughly the same level.
** Issue 13, takes this a step further with a sort of permanent sidekicking ability: two players become, essentially, a duo, and they are always getting experience. If one character is logged out for three months, during which the other character gains twenty levels, then the first character comes back to find they've gained twenty levels. However, not leveling together means that the duo earns ''half'' as much XP as a normal solo character, meaning this is not for powerlevelling.
** Issue 16 takes it even *further*. One of the biggest features in it is "Super-SideKicking", which means that *everyone* on the team is Sidekicked to either the team leader or the mission holder.
* ''RogueGalaxy'' plays it straight, with inactive party members getting a sizable percentage of the XP the active party gets.
* ''ValkyrieProfile'' does it both ways, depending on the difficulty level. On easy or normal, new party members are scaled to your level. On hard, everyone starts at level 1.
**Except Freya, who starts at level 2. And whose stats mirror those of her Easy/Normal self. Because she's Freya.
**Ironically, on Hard you can make people much stronger, due to skills. Funny how that works.
* Absolutely critical in ''BattleForWesnoth'', which even advocates it in the hint system. While surviving any combat grants XP, the lion's share of XP goes to whoever lands the killing blow, so a typical strategy is to use high-level units to bring a powerful enemy to the brink of death and then have a low-level unit finally kill it.
** Also, max level units gain little benefit from leveling up (most gain a minor health boost as opposed to new abilities), making it pretty pointless to give them killing blow XP.
** Since healing doesn't give any XP and many healer units are almost worthless in combat, twinking healers is the ''only'' way to level them.
*''SepterraCore'' has perhaps the nicest possible iteration of this. Not only does everyone share experience equally, regardless of who is being used (mercifully, since only three people fight at a time, and one has to be Maya), but "everyone" also includes those whom you haven't recruited yet. In a sense, the entire party has one experience progression (though characters level at different rates).
* Avoided in ''{{Final Fantasy IX}}'', where you actively have to use the characters in combat to level them up. This becomes extremely irritating when you get Freya, Steiner and Quina back in Disk 3, they can be almost ''ten levels'' behind Zidane, requiring you to spend some additional time training them. Similarly, [[spoiler: players who never trained Quina got an especially nasty surprise in Disk 3, where they are required to use him/her as the only other character besides Zidane in a major boss fight, which means the fight will basically be one-on-one if you didn't raise Quina.]] This troper always makes a point to use all his characters in every RPG he plays, so it was no big deal for him, but the problem's still there.
** Use of this trope in ''FinalFantasyVI'' can actually turn into a [[DiscOneNuke Disk One Nuke]]. Spending a little bit of extra time as soon as you get control of Terra in the Narshe Mines will level her up a good bit. (This troper usually goes up to level 15 or 16, a feat usually lasting an hour, give or take) As you get the next 4 or 5 characters over the course of the next 45 minutes of game time, they will always be one level ahead of your main character, meaning if you level Terra up to 15, Locke will be 16, Edgar 17, etc.
*** However, a bug prevents Celes from learning Muddle in most player's games. It just so happens that the conditions under which this happens (Celes rejoins your party between levels 32 and 39 due to Leaked Experience) are commonly met when Celes rejoins your party [[spoiler:after running off at the Magitek Factory]]. Most players don't even know she naturally learns Muddle.
* Also done in the ''{{Tales Series}}'', with a catch: "bonus" experience achieved due to using certain moves will not be carried over to your non-active party members, and their abilities' usage (which needs to be at a set amount in order to unlock stronger/different abilites) will obviously not be affected.
** In ''TalesofPhantasia'' you start with a character, Chester, which will be lost for a long time afterwards. When you finally meet him again, you other team members will be way ahead of him and he is pretty useless. To make up for it, he gains Level at an incredible rate, making him level about two or three times as fast as the others. This way he can quite easily reach the highest ranks, while the others fall behind. And in remake versions, you'll occasionally get cutscenes in which he trains himself while everyone else is sleeping, catching his levels up to the rest of the party.
*** The remake also features an OptionalPartyMember, Suzu, that can gain a lot of experience to catch up to the rest of the party through an only mildly difficult "trial".
** TalesOfSymphonia plays this straight, but its sequel throws it all out the window. Characters from the previous game appear at a fixed level and do not gain experience. The monsters you capture, however, always start at level 1 (no matter how high level they were in the fight!) but level ridiculously quickly compared to human characters.. but then when they evolve, back to level 1. Though they retain a percentage of the stats they had in their last evolution, and evolution lines loop; so by continually leveling and evolving a critter, it became stronger and stronger and stronger.
* ''KingdomHearts'' also uses the "one experience progression" idea, since party adjustment is limited to swapping out either Donald or Goofy for a world-specific guest character. In ''Kingdom Hearts II'', [[spoiler:the game begins with the player controlling Roxas, whose acquired levels, abilities, and equipment are then passed on to Sora]].
** During the first game, if one wanted to max out Sora's level, the fastest way was to fight [[BonusBoss Sephiroth]] over and over. Only Sora fought in the fight; yet Donald and Goofy leveled too. ThisTroper pictures them sunbathing outside the Coliseum while waiting for Sora to finish LevelGrinding.
* The ''[[DotHack .hack]]'' games also use this, as characters you don't play with for a while gain levels to close to your new level. Justified as the other characters are people playing an MMORPG, and presumably, they still play the MMO when not in your party.
* While most of the characters in ''EarthBound'' joined at reasonable levels, Paula joins the party at level 1 at a point in the game where the main character is likely level 15. The only assistance the player is given is the fact that Paula comes with a Teddy Bear, an item that serves as an attack target for enemies in battle, which might keep her from getting attacked long enough for her to gain a few levels.
** The third character also starts at level 1, but you control him solo through his part of the journey, and, assuming you fight every enemy you encounter along the way, his level will be roughly equal to Ness and Paula's by the time he actually meets them.
** The fourth character to join begins at level 1 as well, during a "Meanwhile..." sequence in which you control him solo during his zen final exam half a world away. The trope is given a halfway nod, though, when the spiritual breakthrough his exam is meant to confer manifests by pouring a load of experience into his empty coffers. He immediately jumps to just high enough of a level to obtain all of his primary psionic abilities (which are gained RPG-traditionally, no more than one per gained level), but still a good ten or twenty below the party's average at that point. This results in an unusual partial LeakedExperience effect, where a certain amount of [[CantCatchUp the antithesis]] also occurs when the player jumps right into the next full-party battle and finds the new guy still sporting definite weak-link traits.
* FinalFantasyTacticsAdvance2 has new members always around the average level of the clan. Ironically, perfectionists aim to get them at a low level so that they have more control over their stat development. After they join, they only get exp if they participate actively in battle, but lower level characters tend to get much more exp.
** Mostly correct, but random unit recruits cap at Level 30. Unique characters are not restricted by this.
** This system is actually improved over the first game, where characters got exp based on the actions they did. A2 gives all characters an amount of EXP simply for being in the battle (with a penalty if they are overleveled), with extra EXP based on how much they actually contributed.
* Likewise in FFT, characters not in a battle don't get XP, and new characters join at preset levels (Not to bad with most, but [[spoiler: Cloud]] and anyone hired from the soldier office will join at level 1 regardless of where you are in the game. And that secret characters joins at the very end. Leaked experience comes from Job Points (Used to learn new abilities), however. Whenever a character gains JP in battle, all characters in battle gain 25% of the JP themselves. This can be rather useful for when you have a character first obtain a job that another character has been using for a while to find theres 1000 extra JP waiting for him.
* You wouldn't expect this trope to show up in an MMORPG, but a new WorldOfWarcraft recruitment deal lets you level up your lower level characters one level for every two levels your recruitee gains.
* In FinalFantasyIV, the ''main character'' is reset to level 1 once he reconsiders some important life decisions. However, the main character usually nearly as strong after the reset as he is before, even though he loses levels, and he gains his first few levels quickly. Once he's been through a few battles, it's actually a common strategy to solo him-- almost everything in the area is weak to the element of his new sword after the level drop-- both because it's easy levels and because of leaked experience. New party members have a set level, but ones that leave and return gain the same experience the main character does while out of the party, and at that point in the game there's only three characters who you've never had in your party, so almost everyone gains the XP from re-leveling the hero.
* Unpleasantly averted in LostOdyssey. Characters not in the active party receive no experience or any other character advancement in the form of Skill Points. Due to a heavy dose of LetsSplitUpGang this can make certain parts of the game brutally difficult, if not almost impossible. Oddly enough however, the game also tries to avoid CantCatchUp syndrome. Characters that are in use level up in very few fights, sometimes leveling up every single battle for a while up to an arbitrary maximum determined by the area you're in at which point all experience gains quickly dwindle to near nothing. For characters who are level dependent on their skills, this allows fairly quick catching up. For other characters reliant on other ways to advance, it's still just down to LevelGrinding.
* ''DragonQuestIV'' [=DS=] has both character swapping and leaked experience.
* Characters earn experience in ''JeanneDArc'' with each action they execute during battle, as long as it hits. Afterwards, a hefty bonus is awarded to everyone in the roster, allowing the benchwarmers to catch up (albeit very very slowly.) Characters can even level up merely from this bonus, and it's not uncommon to have an active participant level up twice --once in battle, and again through the battle rewards. This also allows some of the benchwarmer characters to be used during parts of the game in which some characters who are universally "A team" characters are unavailable and the benchwarmers would be feasible substitutes
* In ''Tactics Ogre'' and ''Knight of Lodis'', each character actually has their own experience set, but the enemies that are often recruitable by Persuasion are set so that they are around the leader's level, and bosses are set so that they actually are a few levels higher than the leader in Knight of Lodis.
* In the original ''Persona'', characters rejoined the party after the prologue at the main character's level, making it much more effecient to concentrate on leveling him up before returning to the school and starting the game proper.
* ''AtlanticaOnline'' is weird in that regard. Being in a group with other players causes LeakedExperience over all fighters, but mercenaries not participating in the battle don't gain any, and all new mercenaries you hire, no matter what level you need to have to recruit them, start at level 1 (or Level 10 in some cases, but that requires you to find a wandering NPC of that class and recruit them for a lot of cash). This also perfectly illustrates why this trope is common, leveling up a new mercenary from scratch is painful as all hell.
** Another variation of LeakedExperience comes with the guild/town system. If your guild controls a town, every resident that is persuaded to settle down in that town gives bonus experience for everyone in that guild.
** Finally, there are ways to acquire Experience Books which any character can read to boost their experience.
* ''GoldenSun: The Lost Age'' gives the lion's share to the active party, but the inactive characters still get half experience.
* ''[[DigitalDevilSaga Digital Devil Saga]]'' partially uses this. Inactive characters automatically gain skill points, but not experience. This actually isn't too bad, as skill points are far more annoying to farm and there's a fairly easily unlocked skill that grants half XP when sidelined. New characters are also equal to, I believe, the average level of the current party when they first join.
* ''GranadoEspada / Sword of the New World'' lets you ''control'' LeakedExperience via "Experience Cards". While completing a quest in most MMOs gives you direct EXP gain, ''GE'' instead gives you consumable items which grant experience to whichever characters you feed them to. Yes, character'''s''': this game lets you own up to 6 characters and deploy up to 3 of them in your active party. But your LazyBackup do not accrue normal-style LeakedExperience, so at that point it's your decision whether to use the Cards to catch them up, or just keep power-leveling your main party.
* Avoided in ''{{Castlevania}}: Portrait of Ruin'', the only game where you control a pair of characters together. [[BlackMagicianGirl Charlotte]] and Jonathan, in addition to sharing Life and {{Mana}} meters, level in tandem, whether both of them are there or not.
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