it makes sense for Jesse and Lake to try and be subtle about the train, to only explain what needs to be explained, and to introduce Lake to the world slowly and cautiously.
but it'd be really funny if they were both just super brazen and upfront about it
like first day back at school everyone's asking Jesse hey man where the hell were you we all thought you died and he's just, all cavalier like 'oh yeah no, I was on a magic train. Would've come back sooner but my best friend from the mirror dimension was stuck and so I had to go back and help her escape or else I would've been haunted by the loss for the rest of my life.'
and everyone pretty safely assumes okay, clearly Jesse has lost it. Something happened but maybe let's not press it. Or at least, teachers and the most mature of the kids aren't pressing it. the rest of them are absolutely asking him more questions about this 'magic train' and 'metal friend' and laughing about the absurdity of it all later behind his back.
and everyone thinks it's very funny and hey Jesse being completely bonkers is probably better than him being dead, so it's okay to laugh.
it's all well and good until Lake starts showing up.
It only takes a few days for Lake to get bored sticking around alone at Jesse's house (also these two have massive amounts of separation anxiety after the train) so Lake absolutely starts heading out to wait for Jesse after school so they can walk home together.
Suddenly it's not haha very funny Jesse telling these wild stories about a train and metal people. Suddenly it's an actual person made of metal, just blatantly waiting by the fence daily, sitting there reading a book or drawing or whatever, somehow seeming entertained and at peace with even the most mundane of things until Jesse comes out.
And people have asked, of course they have, and Jesse and Lake are just upfront about it. Jesse simply looks confused and says 'yeah no, this is Lake? I already mentioned them? I told you she's made of metal, that's not- i would not forget to mention that detail. it's an easy one to remember'
some kids accuse Lake of wearing some sort of costume or painting themself or something, so Lake just crushes some stones in her hands and the next person who wants to doubt them can try something and see what punching a solid metal teenager feels like on your bones.
other than having to occasionally assure people that there's no trick, Lake and Jesse just treat the whole thing like it's completely normal. Lake is from another dimension, they were friends with a deer with laser eyes, did you know all our reflections are actually alive and sentient? disturbing but true!
it's all so blunt that all anyone can really do is just... accept it. sure. that doesn't sound right, but I don't know enough about metal people to disprove it, and the world is already so goddamn weird, this might as well happen too