He doesn’t really think about the mice, since they’ve been there all along.  However, they’re just the beginning.
Lance is wandering past Pidge’s room a few weeks after they’ve all returned from where the wormhole had thrown them when he sees something out of the corner of his eye and backpedals.
“What the heck are those?”
“Hm?”  Pidge looks up from her monitor and follows his gaze. “Oh.  I brought them back from the Trash Nebula.”
Lance stares at the fuzzy things hovering near the wall.  One of them is green, the other yellow, and they don’t seem to have mouths, just eyes and some kind of triangular patches.  “Why?”
Pidge shrugs. “They were nice to me,” she says, and what does that even mean?
Still, it doesn’t really bother him until Keith comes back from the latest planet they landed on with something else.
They all stare at the blue wolf with varying degrees of bemusement.  Shiro’s the one who speaks up.  “…Keith?”
“He followed me home, can I keep him?” Keith deadpans, because of course he does.
Pidge comes at the wolf with an instrument in her hand, but suddenly the wolf is gone. Â She stops in confusion as they all stare around the room, finally spotting the wolf at least six feet away with its back against the wall.
And that just is not fair, because why does Keith get a teleporting Space Wolf?
 The next one to pick up a weird alien pet is Hunk, and this time it’s not so easily accepted.
“Where…exactly did you get that?” Allura demands, keeping her distance from the thing that looks like an alligator with a sharklike head.
“Oh!  He tried to eat me, and when I ran away I dropped some food goo packs and he ate them and now we’re friends!”
Even Coran looks a bit concerned at that.  “Hunk do you think it’s really a good idea to–“
He stops speaking, because Hunk’s alligator suddenly changes color to blend in with the floor as if it’s equipped with Pidge’s cloaking device.
“No!  No way are we keeping an invisible murder-lizard in the castle!” Lance says.
Hunk looks indignant.  “He’s not a murder-lizard!  He’s my friend!”
All of them try to dissuade him, but Hunk is adamant. Â Eventually they agree to keep the lizard for a trial period, but leave it on the nearest planet if there are any problems.
There are no problems, apart from the lizard’s tendency to sneak up behind people and wrap its tongue around their leg, a habit which only Keith finds amusing. It's perfectly happy to eat food goo and whatever else Hunk makes for it, despite the fact that it’s clearly specialized for eating meat.
“Man, why does everyone else get cool space pets?” Lance complains one day from his seat slung upside down in the lounge.
Pidge answers him without her fingers even pausing on the keypad.  “’Everyone’ doesn’t.  Coran and Shiro don’t have any.  Besides, you don’t need a pet, you have Kaltenecker.”
It's only absolute loyalty that keeps Lance from retorting that while Kaltenecker is perfect and beautiful, she isn’t a space pet.
Shiro’s pet is a bird, with a crest and a tail that hangs half down his back when it perches on his shoulder, that cycles through different pastel colors depending on its mood.  Whenever they’re on a planet Shiro sneaks fruit for it from the bushes.
Keith comes into his room a few weeks later.  Lance looks up, suspicious, since Keith has only come to his room a handful of times before.  “What is it?”
Keith sighs. “I figured I’d get you something, since you’ve been whining.”
“I do not whine!” Lance retorts automatically, even though he has no idea what Keith’s talking about.
Keith rolls his eyes.  “Whatever,” he says and reaches into a pocket.
Lance opens his mouth to keep arguing when Keith hands the thing to him and he feels his mouth falling further open.
It’s a mouselike animal, small enough to fit in the palm of his hand, tail curled around it, glowing softly green.
Lance stares at Keith for a moment, speechless.
Keith gives a rare grin and a two-fingered salute, turning to leave the room, shooting a “You’re welcome,” over his shoulder.
