In Dark River when the other clans want to drive RiverClan out, the loudest protesters are Firestar and Sandstorm. Although at first, it seems like them acting normal, they're actually remembering what happened to SkyClan and they don't want RiverClan to become forgotten like SkyClan. — Lightflame
In The New Prophecy, it makes no sense that StarClan sent a group of cats to find out about the impending destruction of the forest when they could have just told them. Then, when thinking about what the series would have been like without said seemingly pointless journey, I realized it did have a point. All the clans needed to unite to find a new home, and StarClan sent out cats who would learn to trust each other on the journey so that when they came home, they could unite the clans together without fighting! A much better solution than simply telling them to unite. —Lightflame
Plus, it also paved the way to their new home; they would have had a tougher time finding their new home if the sent cats hadn't gone to sun drown place first and then acted as guides to their Clans. —Reika
Also, recall the whole "unite or die" thing from the very beginning of the Clans? Yeah, look at how that worked out. StarClan would have known that if it didn't work the first time, when the divisions between the cats weren't as strong, then it certainly wouldn't work when they'd developed loyalty to their own Clans and animosity toward the others. —Flametail von Karma
If Tigerstar's plot was to unite all the clans by force anyway, then what was the point of executing Stonefur, Feathertail, or Stormfur based on them being HalfClan? Easy: He either was going to wipe out ThunderClan anyway and wanted to get rid of any ancestral links, or he really wanted to take make dirt on Bluestar and Firestar (by the proxy of Graystripe), since Mistyfoot and Stonefur were the former's kits and the deaths Feathertail and Stormfur would hurt Graystripe (and by proxy Firestar) —terlwyth
Many fans wonder why in the Clans' mythology, there are only three Great Clans and not four. Some add in a fourth, CheetahClan or JaguarClan. However, the reason there are three is that lions, tigers, and leopards are all members of the genus Panthera. Neither of the two common fourth Clans would work, as cheetahs are from the Acinonyx genus, and thus are no more related to lions, tigers, and leopards than a house cat, while jaguars, although they are members of the Panthera genus, are New World animals, and until the New Prophecy made it into a fictional location, the series was set in England. —Goldenpelt
In Warrior Cats, the character Darkstripe was always an interesting point of story to me. Darkstripe had established himself as loyal to Tigerclaw until Tigerclaws treachery was exposed, and Darkstripe chose not to follow him only because Tigerclaw had left him out of the loop regarding his plans; he was offended that Tigerclaw didnt let him in on his planning, despite establishing himself as loyal to Tigerclaw. A few books later, Darkstripe becomes the eyes and ears for Tigerclaw after he becomes the leader of Shadowclan. After getting kicked out of Thunderclan in the next book, Darkstripe joined Tigerstar and the Riverclan-Shadowclan alliance, only to be beaten by a weakened Riverclan cat and likely losing favor in Tigerstars eyes as a result. Next thing you know, Tigerstars dead, and Darkstripe now has nowhere to go, and dies in the final battle not long afterward, with nothing left for him after Tigerstars death. Why? Because Darkstripe had seen Tigerstar as a father figure throughout the series, which is made even more interesting by the fact that Darkstripes biological father was revealed by Word of God to be a character that was dead before the series had officially started, so there was no other cat for Darkstripe to look up to other than the one that was once his mentor. That was why Darkstripe was offended by being left out of the loop, that was why Darkstripe was so eager to prove his loyalty to Tigerstar after joining the alliance: Darkstripe was a "Well Done, Son!" Guy that just wanted the approval of Tigerstar. This makes his Famous Last Words all the more brilliant without Tigerstar, there truly was nothing left for him to live for. Battra 09416
Mapleshade is almost an Evil Counterpart to Bluestar. Both started in ThunderClan only to fall in love with a RiverClan tom. But Bluestar stayed with her clan while Mapleshade left. - LOAD
Ivypool is the normal one of the Warriors protagonists. While all the other ones get their Warrior Names from doing an exemplary act, she gets her from doing a hunting assessment. - Lightflame
Similarly, every cat used to get warrior names from doing exemplary acts in the first series, but then later on it was usually a hunting assessment. This seems like another example of Early Installment Weirdness, but it is actually because Firestar was trying to atone for Swiftpaw's death, which would have never happened if it had not been required for him to show heroism in battle to become a warrior (thus why Longtail blamed him for using Swiftpaw as a messenger). Thus why cats get assessments under Firestar's leadership, but not in the first series or the prequel Super Editions.
A lot of the anticlimactic villain deaths in Warriors can be explained if you approach the series with this in mind. "No villain deserves to go out in a blaze of glory." - Lightflame
Great StarClan, this was actually confirmed in The Last Hope. - Lightflame
Many of the leaders suffer the loss of many of the cats they loved, and grieve heavily for them. This is so they can all come back one last time to give the leader their nine lives.
Harveymoon of all cats is a Foil to Sol. In After the Flood, Harveymoon becomes genuinely helpful instead of a Lazy Bum, and he proves his worth as a SkyClan warrior. Meanwhile, Sol becomes worse, and is exiled at the end. The difference is how one grew up and the other didn't. - Lightflame
Jayfeather almost instantly likes Dovewing, and rarely finds himself annoyed by her, despite how much she bothers Lionblaze, and how he doesn't think of Ivypool nearly as fondly. Since Jayfeather places a high value on the bonds between siblings, its likely that he subconsciously remembers her as his sister Dove's Wing, causing him to naturally feel a bond with her. -Lightflame
Jayfeather's name, in light of The Reveal that Leafpool and Crowfeather are his parents. Leafpool named him after his father. -Bio Safety
Why was Cloudtail Cinderheart's mentor? Because Cinderpelt's original mentor was Firestar, who like Cloudtail, was mentored by the current leader, was thought of as the leader's surrogate son, and was born a kittypet!
I think I know why Jaggedtooth betrayed ShadowClan and joined BloodClan in The Darkest Hour. He helps Tigerstar become leader in Tigerclaw's Fury, but Tigerclaw basically goes "Screw you, Jaggedtooth! I don't own you anything!" So Jaggedtooth must have felt so betrayed at the moment that he waited for the time to join BloodClan. -Wildstar93
The disastrous vole omen Goosefeather receives in Bluestar's Prophecy seems like a misinterpretation on his part, but it actually is accurate. In the battle, ThunderClan is flattened by WindClan, just like the vole predicted. The shred of catmint, a medicinal herb, on the vole's flank? It was a medicine cat who murdered Moonflower.
Brambleclaw's and Tawnypelt's reactions to being told the truth about Tigerstar's crimes are representative of the Clans they end up with. Brambleclaw stays with his birth Clan and trains himself to the best, most noble, most loyal warrior he can possibly be, as fits a ThunderClan cat. Tawnypelt does the more pragmatic thing; instead of spending her whole life with cats who will never fully trust her because of her parentage, she finds a place where she will be judged for the warrior she is instead of the tyrant her father was, in ShadowClan.
Aside from the fact that Greypaw said that Lionheart was more experience at being a warrior than Tigerclaw, there is another, deeper reason why Bluestar didn't appoint Tigerclaw deputy: he said he killed her mate, Oakheart!
You may not realise it, but let me run through the deputies of ThunderClan in Into The Wild. Redtail, a deputy who we hardly know, is killed in battle against a rival clan. Lionheart, appointed deputy after that, is shown to be very diligent, loyal and noble, the ideal future leader when Bluestar looses her remaining lives. Sadly, he's killed too. Enter Tigerclaw, who is the Big Bad for this arc and is exiled later on. Prophecy for the end of this season? "Four will become two, Lion and Tiger will meet in battle, and blood will rule the forest." Red is the colour of blood, and Scourge appears out of nowhere to kill Tigerstar. TigerClan is ruled by the ambitious Tigerstar, and LionClan is lead by the noble Firestar! -Thomasfan
Everyone's saying that Mapleshade was cruelly kicked out of Thunder Clan for having a tom's kits from another Clan. And, I do agree that it was cruel. But... they say that cats like Bluestar/Oakheart, Graystripe/Silverstream and Leafpool/Crowfeather had done the same thing and they were not kicked out. Well, here's the thing. All those cats were born after Mapleshade's time. Stories have likely been told to the cats of the four clans about it. In other words: the clans have learned from what happened to Mapleshade and her kits and don't wish to make that same mistake again!
It's established that dead cats fade away if they aren't remembered. StarClan never seemed all that invested in keeping SkyClan's memory alive. They were knowingly condemning SkyClan's cats to a gradual, total death.
However, according to Word of God, Cloudtail would probably go to StarClan but be very surprised, which also applies to Mothwing.
When one realizes that before Tigerstar, if you were condemned to the Dark Forest, you were stuck to wallow in isolation for the rest of your existence.
This is the point of the Dark Forest. Clan cats only go there if they have committed extremely severe crimes, and being forced to walk alone in a cold, dead forest forever is part of their eternal punishment.
In Secrets of the Clans, a kittypet/loner named Floss has her newborn kits taken from her by the Twolegs who own the barn she lives in. Since they didn't let the kits stay with their mother until they were old enough to eat solid food, it's very likely that they were taken away to be euthanized.
Scourge's soul disappeared after he died, because he didn't believe in StarClan. Which is all well and good, because he was a sadistic murderer. But what about all the friendly kittypets and loners that don't believe in StarClan or are unaware of its existence, including Princess, Smudge, Barley, Cody, Jake, and others? Are they also condemned to Cessation of Existence when they die, assuming there isn't a separate afterlife for them?
I'm pretty sure it's been confirmed that kittypets and loners have a separate afterlife. We do see Jake as a spirit at the end of Tallstar's Revenge and it was confirmed that Tom is in the kittypet afterlife.
The Clans live in relatively close quarters together, and each individual group has a fair number of cats. Diseases like greencough are shown to tear through the territories quickly and relentlessly, now imagine if the Clans ever faced a rabies outbreak...