I can see it in the glasses, which make him look older, and the "taking Gil under his wing" covered by Sturmvoraus bluster and the aristo social expectations of who becomes the "lackey/minion." I can't see it as easily in the fact that Tarvek ultimately allows Gil to be the leader of the two to the extent it sounds like, or the wistful wish that they were brothers. Even accepting that Tarvek's real family just stinks, it feels slightly off to try to adopt a younger kid in, rather than an older one or a very-close-in-age peer...and VERY off for a little boy to let himself be led by one who's not only younger, but a social outcast.

It feels like it would have had to be a truly amazing friendship for that to have happened very easily. Little boys are so intensely involved in their ranking systems at that age...or they look like it from the outside, and from the developmental psyche material I've read.

I can see Tarvek a bit older, and a bit younger, but basically I see the two as being almost the same age, so much so that barring minor kid-teasing they would not themselves take the age gap seriously. Much beyond a year and the younger one becomes one of the "little kids."