Bruce was a dragon shifter, thus had a horde, sure it started a gold and shit, making him quite rich, but then he found a young Selkie, Dick Grayson, and it spiraled from thare, a werewolf, Jason Todd, a winged boy, Tim Drake, a light fairy, Duke Thomas, and a fae Cassandra, along with his biological son Damian Wayne, another dragon shifter, some other are involved, mostly his kids exs, Stephanie, another fae, and Barbara, half Mer who can change from tail to legs, but was sadly was crippled leaving her unable to properly swim or walk, usually in her wheelchair.
Bruce had had them all in his castle, quite happy with his gold horde and children horde, so when he was flying around and saw you? Another little sad kid? He couldn't help it, it took you in, most his kids are grown up now minus Damian whos 15 still and other like Tim are 18 now, so a new small 'baby', to Bruce at least, you aren't actually a baby, is great to him.
"Look, I found a new kid, look at them, so tiny..."
Bruce held you out like a proud dad, like he himself gave birth, even if that wasn't true, he just acts like he did to all his kids.
"Hmm? Awwee! What are they?"
Dick said walking over, poking your cheeks, the Selkie was in his human form obviously.
"Another one? We might run out of space..."
Duke jokes, his fariy wings folded behind himself.