Gilgamesh has a BROTHER?!

[Toodles]

Gilgamesh can change size and shape, see: FF5 and FF14...

That's true, touché. I wasn't thinking about "Morphin' Time!", other statements still stand though.

If SE wanted to make Yojimbo the brother of Gilgamesh, they could without retcon.

[lololink]

That's true, touché. I wasn't thinking about "Morphin' Time!", other statements still stand though.

If SE wanted to make Yojimbo the brother of Gilgamesh, they could without retcon.

Except that it wouldn't make any sense and that it would be pointless.

[JTribal]

Except that it wouldn't make any sense and that it would be pointless.

Why, because you don't like the idea?

[lololink]

Why, because you don't like the idea?

Because it defies all logic, even for a fantasy game.
1st, Gilgamesh is a weapon collector, Yojimbo is only collecting money ( he is a Bodyguard, his name means Bodyguard ).
2nd, Gilgamesh is more or less immortal ( or too cartoon to be killed ) while Yojimbo cease to exist when the prayer stops at the end of FFX.
3rd, Gilgamesh has his own will, while Eons in FFX are just summoned and bend to their master's will, therefore they can't be the same guy.

Same reason they can't be brothers, Yojimbo doesn't have any mother, he can't have brothers...

[Sigiria]

Why, because you don't like the idea?

Well, Yojimbo litterally mean bodyguard. Because he was that kind of Faith in FFX.
In FFV (where spawned Gilgamesh) they were also random ennemies called yojimbo, it would be kinda weird to take one of FFV mobs and FFX special summon and suddenly make it brother of the only character to have crossed several games (not accounting promoting fate).
It would also be redundant as Enkidu is a brother figure to Gilgamesh.

Wouldn't be surprised to see him in the game, not even surprised to see him in one of Hildibrand quest. But I really don't see how he could be Gilgamesh's brother. Their family would have a terrible luck to have 2 brothers sent through the rift only to meet back in Eorzea.