In Ouran High School Host Club, Honey gets this reaction from pretty much every female (and some males) that see him, being a senior but having the rough size and appearance of an incredibly adorable blonde eight-year-old, particularly when he's got his stuffed bunny with him, as he usually does. He's even more sugary than the sweets he's almost always seen munching on-but watch out, he's not exactly a pushover when it comes to a fight!
In Mahoraba, the eccentric president of the occult club takes an intense liking to Asami-chan, who is the first person to be so innocent that she finds her creepy jokes funny.
Ranma One Half: Azusa Shiratori is very prone to this, grabbing new "cute" items and giving them a French name, and then claiming ownership of them. If it resists, she'll knock it out. If it's yours, and you resist, she'll knock you out. In the anime version, she tries to "adopt" a half-eaten rice cake soon afterward. When Genma manages to polish it off before she can steal it, she screams in horror and beats him senseless. Her collection, in the few glimpses we've seen of her mansion, has been shown to include an octopus balloon, a stop sign, and even weirder things. In an anime-exclusive episode, she adopts a Tanuki statue — and when Kunô cuts his way out of it (it fell on him beforehand), she promptly adopts him as well, thinking he must be a real tanuki.
In Kannagi, Nagi sees a pair of kittens curled up and sleeping outside of Jin's house. She finds them so irresistibly cute that she wants to take care of them herself. Jin's not too keen on the idea, as his current living arrangement prevents animals from taking up residence inside.
The pet store clerk in Chi's New Address does this even after discovering Chi has an owner. The reason she can't have one is because her little brother is afraid of cats — but as it turns out, her brother happens to be Yohei's friend Ryu, who got over his fear about 20 episodes before this was revealed.
Yuki Nagato, of all people, reacts this way in The Melancholy of Haruhi-chan Suzumiya when she finds the newly revived "Achakura", proceeding to place her in her bag and literally take her home.
Tsuruya said this about Mikuru in a waitress costume.
Don't forget the original case, where Haruhi practically kidnaps poor Mikuru because of her moe factor. We get to see it from a slightly different perspective in Disappearance, where it's just as hilarious and extremely awesome to boot.
Macross Frontier. Ranka Lee does this to a little cute squirrel thingy which she later names Ai-kun. However with this being Macross, said trope is inverted when it is revealed that Ai-kun is a Space Vajra larvae, who takes Ranka home with it later. Of course, it's arguable that the Vajra were trying to do that with Ranka in the first place
Teresa "Tessa" Testarossa gets this reaction when she introduces herself to Kaname's high school class in Full Metal Panic? Fumoffu. All the guys go "WOOOAH!" while all the girls cry "Oh she's so cute!" with accompanying love hearts.
Sōsuke evidently elicited this kind of response when he was young. Just like in the trope description, his Cuteness Proximity was so incredibly intense, it managed to melt the hearts of war-hardened veterans and pretty much made them internally Squee that they want to take him home and make him their child. Which they then proceed to attempt to do. He certainly never lacked people who were all too eager to take him in as their own. Starting with Majid, an Helmajistani rebellion leader whom Sōsuke had tried to assassinate, who liked him so much that he adopted him as his "Son of Bdakshon's Tiger", and raised him with complete kindness. And then there was Kalinin, who wanted Sōsuke as his son from the very beginning, and took him as a prisoner of war after Sôsuke tried to assassinate him. He then proceeds to persistently try to get Sōsuke to agree to be his adopted son (which he refused, since he already had Majid as his "father" — yes, it got to the point of being a first-come-first-serve basis). After Majid dies, Kalinin finally manages to force his way and get Sōsuke to be his legally adopted son. And all while that was going on, Gauron has tried to take Sōsuke for himself ever since the moment he first set eyes on the boy. He literally did a double take, parked his jeep, and tried to lure Sōsuke to come with him by promising him food and ammunition. Sōsuke refuses, and Gauron ends up being unable to forget him for the next five years. (Though in Gauron's case, it's more of a pedophile rapist, sexual version of wanting to take him home, unlike the previous two).
Kiko: I'm not into lolicon. Besides, that's illegal.
This may be a Shout Out to Rena, since she uses exactly the same phrasing ("Omochikaeri~!").
In Fullmetal Alchemist, Alphonse has a tendency to pick up cats and keep them in his armor. Edward is not happy about this. Referenced HILARIOUSLY when Ed assumes Al's found another cat in an alley. Except it's not a cat, it's Ling.
Though not to the point of the trope's name, after Tohru's initial encounter with Kisa in Fruits Basket, the latter follows the former around for the duration of her stay. While Kyo cracks that it would bug the crap out of him, after Tohru stops walking and Kisa bumps into her, Tohru squeals and glomps her. After Kisa leaves, Tohru mentions her slight sadness at not having her around. Later volumes of manga have scenes where other characters are talking and the reader can see little hearts floating into the more serious panels, revealed to be emanating from Tohru and Kisa hugging each other. Every time they see one another, Tohru has the same squeal-and-glomp reaction.
In the ARIA manga, Akari attempts this on Albert, after seeing him helpless with his filled-up boat, as seen here.
Rena Ryuuguu from Higurashi no Naku Koro ni is the Trope Namer (See the Visual Novels section), and is well known for doing this. Hell, the running joke in the series is that if ever someone gets kidnapped, Rena would be the prime suspect!
The cold-hearted, and, at times, cruel Battle Butler Sebastian in Black Butler is shown to adore cats of all types because "there is nothing cuter." It's later revealed that he actually picked up several stray cats and kept them in his wardrobe.
This is Kyrie's reaction toward Toppi from the World Destruction manga when Toppi and Morte save his life. Toppi does not take being called "cute" well.
Eisuke Kitamura in Stepping On Roses (Hadashi De Bara Wo Fume) appears to have this as his motivation for constantly bringing home orphaned children... that is, until he reveals that he really just wanted them to work for him in his future business endeavors when they get older.
In Panty & Stocking with Garterbelt, Stocking has this reaction when she sees the Sperm Ghosts. Admittedly, for being the ghosts of vengeful wasted sperm, they are pretty adorable.
Iris from Pokémon: Best Wishes tends to react this way around the Monster of the Week. Her actions usually result in the Pokémon hiding from her or attacking her.
While Sasha in Seikon No Qwaser is still going through amnesia, he almost gets kidnapped by a Mikuru Cosplayer.
Gajeel Redfox in Fairy Tail, hilariously enough. He spends most of his time being an utter grouchy badass, but has an obsession with finding a cat companion to call his own. And when he finds the perfect one, he is very adamant on bringing said cat back with him. Do note said "Cat" is one of the most badass animals to ever grace a manga's pages. In this case however, it's less about cuteness and more about, as his two fellow Dragon Slayers have cat companions with them, he figures he's lacking as a Dragon Slayer if he didn't find one as well. Pantherlily's badassness is exactly why Gajeel likes him.
One story in the Shoujo Jump edition had a girl who helps a friend (boyfriend?) catch a wild rabbit in a snare. After accomplishing the deed we see into her mind the scenarios of her keeping the rabbit as a pet (feeding it, giving it it's own little house, etc.) much to her friend's chagrin. She's horrified to discover that her friend has a more "culinary" interest in the animal, and she lets it escape.
A more serious example occurs in Bleach where in Riruka's flashback, she had done this to the guy she had a crush on, imprisoning him inside her treasure box. She stopped when she realized how badly her powers were affecting the guy and let him go. More exactly: Riruka actually weaponizes this trope. Anything and anyone she finds cute, she can snatch it with her powers and keep it for herself. She started with petty theft as a little girl (stealing the heart-shaped necklace of the neighbor that bullied her), then used it as described above.
A creepy (though hilarious) version happens in chapter 210 of D.Gray-Man. A random gangster who, according to his crony, "loves all beautiful things to a sick degree," decides that Kanda is the most beautiful person he has ever seen and declares, "I'm going to kidnap him and bring him back home!" Kanda promptly beats him to a pulp.
Katanashi in Working is a minicon — someone who thinks anything tiny is inherently cute. Showing him anything small is guaranteed to get this reaction from him — which can be creepy when the object in question is a four year old girl who got separated from her mom. He invokes this one by name when the already-tiny Popura curls into a ball.
This is Alice's reaction when she finally encounters Yune in Ikoku Meiro no Croisée, which is entirely understandable, given that Alice is a 19th-century Occidental Otaku meeting an actual Japanese person for the first time and that Yune is just that cute.
In Kotoura-san, this was played with in episode 2 when Haruka first meets Yuriko. The latter is ecstatic to meet the former, and attempts to carry her to the ESP club room. Downplayed as part of the reason was Haruka is telepathic.
A voicepack for Suika, of all people, has this very phrase in it. Makes sense, since Oni are traditionally known to carry people off when they lost contests, and Suika is strong enough to carry away anyone she'd want. Fans have taken to joking about taking her home, and then get rebutted by other fans saying that Suika'd take THEM home instead.
The Hill Of Swords: Any time Tabitha shows her vulnerable side, Shirou has to suppress an urge to take her home and give her "adorable ponies and dollies and pretty dresses".
In Magic Trick, England uses his powers as Britannia Angel to turn Italy into Chibitalia. Everyone, from the Allies to Japan to frigging Prussia are so overwhelmed by his cuteness that they each want to bring him home with them. Generally, Chibitalia is fine with this. Except for Germany, because he thinks he's scary.
Films — Animation
In Finding Nemo, Dory the blue tang wants to do this with a cute, very small jellyfish... until she learns that jellyfishes sting.
In The Lion King when Timon and Pumba first run across Simba, Timon's first reaction is to panic because of, well, the food chain. Pumba meanwhile thinks Simba's such a cute little guy that he asks, "Can we keep him?"
In Battle Royale, this is Hiroki Sugimura's reaction to stray cats... and his classmate Kayoko Kotohiki.
In the novel Five Children and It, a group of children find a magical creature called a Psammead who grants them all a wish a day. In a moment of misguided altruism, they decide that the one among them who can't ask for a wish (a baby) should have his wish granted, only to learn that his wish is for everyone to want him.
There is a picture book called Children Make Terrible Pets. The story is about a young bear named Lucy who finds a human boy out in the woods. She takes him home, names him "Squeaker" and tries to make a pet out of him. Read that title one more time....
In The Time Machine, the Time Traveler has encountered a race of people who are essentially humans that stop developing physically and mentally at age six. He has fallen in like with one of the womenfolk. "Weena I had resolved to bring with me to our own time." (Ch. 7)
Subverted in Dune, and combined with I Have You Now, My Pretty. The Harkonnen's Mentat Piter de Vries wanted to keep Jessica Atreides for himself, but quickly dumps the idea when the Baron offers him to stay and rule Arrakis in his name instead.
"The Kidnapping", by Shiga Naoya;; The narrator sees a little girl and decides that he must have her for his own.
Legacy of the Dragokin: Zarracka has a new goal; in addition to killing Daniar she's also going to replace her as Benji's mother. Because of this a number of plot events take a different turn then they would have last time.
Liz does this accidentally on Thirty Rock. When handed the baby of a coworker she has such an extreme case of Cuteness Proximity that she goes into a fugue state and realizes that she is now in her apartment... and still holding the baby.
Liz: It was like highway hypnosis — you know, when you pull into your driveway and you don't remember driving home. Pete: Oh right, and you have someone else's baby in your car.
Ryutaros from Kamen Rider Den-O is very fond of cute animals and tends to bring them back to the DenLiner, sometimes regardless of whether they're homeless or not. Reaches an extreme when he does it to a fellow Imagin, which introduces the cast to Sieg...
Stargate SG-1. Samantha Carter makes friends with a little alien boy in "The Nox". O'Neill informs her drily that, "No, [she] can't keep him."
World's Weirdest Restaurants: The host mentions this when holding a baby monkey in his arms at a restaurant which uses monkeys as servers.
Perhaps Guy Kyser — frontman of Thin White Rope — tossed a few too many oblique words into the salad, but (in the song "Take It Home") he seemed to be evoking this trope. Or attempting to explore the boundaries of its inherent futility:
Something moving in an airtight room Doesn't age a minute for a year in a vacuum But dies on the way home[...] I can't take this one home I can't take this one home
Yukari is said to spirit away people whom she takes a fancy to. This includes taking home people from outside Gensoukyou.
In Phantasmagoria of Dim Dream, Yumemi decided she wanted to take home one of the magical denizens of Gensoukyou, For Science!!
After spending most of Undefined Fantastic Object geeking out at the prospect of meeting an alien Sanae refuses to believe Nue is a youkai, and after she defeats her drags her off to take pictures with her.
In the spinoff manga Inaba of the Moon and Inaba of the Earth, the Moon princess Watatsuki no Toyohime repeatedly tried to take home one of the Earth rabbits she found while visiting Eientei.
If you bring your Mabari War Hound to the city of Denerim in Dragon Age: Origins, he will abruptly run off and return a cutscene later with a small boy in tow. The boy just jumps up and down excitedly shouting "PUPPY!" You have to convince your dog to take him back home.
Shirou took Ilya home (and Taiga approved) in Fate route despite the fact that she was an Ax-Crazy enemy of his only five seconds earlier, and tried to kill him, Saber, Rin, and Archer, and abducted him once.
On the other hand, Ilya had taken Shirou home in quite a few of the Bad Ends. Taken home in pieces that is.
Rena Ryuuguu◊ of the mystery-horror franchise Higurashi: When They Cry is the Trope Namer. Whenever she sees something she regards as cute, she melts into a complete ditz and fawns over the subject of cuteness like a mother/big sister. Occasionally, she takes it a little too far, as the followingvideos show the frightened audience. However, sometimes what she perceives to be "cute" can be odd if not downright disturbing to more normal people.
Apparently, this attitude is contagious. Keiichi starts to act this way (most likely as a joke) when confronted with Shion in her Angel Mort uniform, and Irie acts like this in a couple scenes, though it's not as cute.
In The Lounge, for a while it was a running gag for people to see the very petite Jamie MacKenzie and equally short (but teenage) Max Espinoza and ask how much they cost. Usually when they were wearing a cute hat or costume.
The Inexplicable Adventures of Bob!: When an unleashed giant monster turns out to be cute and harmless, Molly names him Snookums and wants to keep him as a pet. Conveniently, he ends up shrinking to the size of a basketball by the end of the storyline.
Gaijin Smash: Azrael once had a student so adorable, he told his fellow teachers that he wanted to kidnap her. No, no. Not for anything bad. The police would find them having a perfectly innocent tea party.
In the MSF High Forum, Demona has this reaction to Lily, the chibi-Pettanko-Succubus. Lily, at present, is begging for death.
In Snoopy Come Home, Snoopy comes across a little girl who, without warning, grabs him and drags him to her home, shouting, "Oh, boy! I found a dog!" When Woodstock tries to save Snoopy, the girl takes him too.
An episode of The Powerpuff Girls had Bubbles bringing home animals she felt sorry for. This culminates with her trying to hide a baby whale from the Professor.
Elmyra of Tiny Toon Adventures has no problem with snatching random creatures (in a world of Funny Animals) and declaring them her pets. Compounding matters, she's also a negligent owner whose pets invariably die. In many ways more sinister than her mentor, Elmer Fudd, who would simply shoot at them.
Tex Averydid it first. "Hello George! Glad to know ya, George! You're my new lit-tle friend, George! My new lit-tle friend. What I'm gonna do is to pet ya and play with ya, George!" (crunching of bones in a hug)
A rather odd example in Jonny Quest The Real Adventures. Villain Jeremiah Surd and his minions have hijacked Air Force One and they plan to kill everybody in it with a deadly nerve gas. Our heroes Jonny, Jessie and Hadji get themselves captured while trying to rescue the President. Bandit (Jonny's pet dog) is also there. When Lorenzo, one of Surd's minions (who is usually very competent in his ruthlessness, except for being rather Book Dumb) points Bandit's presence out to Surd, the boss tells him to "throw him in, too." And Lorenzo goes: "But he's so cute! Can I keep him?" Surd, predictably, says no.
Generator Rex: One episode has Breach kidnap Rex to put in her dollhouse while referring to Rex as her "new favorite" and "shiny thing."
Adventure Time with Finn and Jake, in the episode The Jiggler, Finn and Jake find a creature that dances along to the song that Finn was singing and the two take it back to their tree house to party with.
The Boondocks did this with Riley of all people being kidnapped by one of Grandpa's blind dates because he was just so cute. Huey and Grandad had to go save him.
In the Teen Titans Season 2 episode "Date with Destiny", Beast Boy makes mention that Killer Moth's mutant drones are cute enough to keep as pets (in the larval stage). Despite Raven's warning, he manages to hide Silkie up until Season 3's "Can I Keep Him?"
Po: Oh please, please can we keep him? Can we keep him pleeeeease? He's even pottery trained!
The reason inter-species adoptions are possible — e.g. a dog with puppies adopting a baby bunny it might have normally had for breakfast, a she-wolf adoptinga human infant, etc. More specifically, facial features with certain proportions (huge eyes, tiny nose, tiny mouth, round head) really hit an onlooker's maternal instincts, and happen to be pretty much universal among mammals, so that sometimes, under the right circumstances, the instinct to take it home and care for it overweighs the instinct to snack on it.
Outside of mammals, there is an adorable story of a snake taking his would-be-food in as a friend. A snake in a Japanese zoo wasn't eating after being added to their exhibit. They thought maybe it wanted something more... lively. One of the caretakers figured that the snake may have caught on with their trick, since normally they use warm meat to trick the snake's senses into thinking it's still alive and snakes won't eat dead things unless they have to. They placed a hamster in the enclosure with him and... they started cuddling. Turns out the snake was stressed from the trip and started eating again, with the hamster as a companion.
Many a puppy has got their home because of this trope. People might start out with the intention of just having a look but then a puppy jumps up to say hello, climbs into their lap, or just gazes at them with those big brown eyes and suddenly said puppy coming home with them is a forgone conclusion. Also occurs with older dogs, especially ones that qualify as woobies.
According to con reports, the creepier members of Fan Dumb have a habit of asking Doug Walker if they can "keep" him. As one might expect, he doesn't enjoy this.