Since Steve is such a good babysitter, kids have a habit of flocking to him, even if he isn't with the Party. On more than one occasion, he encounters supernatural kids (ghost children, werewolf puppies, witchlings, etc) and has to briefly look after them when they recognise him as Safe.
Preferably, Steve at least recognises that something is unusual with the kid/s, even if he doesn't know exactly what, rather than being totally oblivious.
Some of the other characters then have to drag him away from a pack/coven/etc that would be all too happy to take him back with them along with the kids once they're reunited.