
If you have true and passionate reasons for your ideals that you decided for yourself were following, you’re someone to be respected in Gil’s eyes, regardless of where your morals fall. If you’re willing to do whatever it takes for your ideals and believe in them passionately and aren’t just taking them from someone else, he’s nearly guaranteed to like you. It’s a breaking of the status quo, of the old ways, that Gilgamesh likes. They turned up out of the blue and decided to throw hands with this stuck up douche who’s never been truly challenged before. Enkidu was created specifically to be Gil’s equal, but they don’t approach him like it’s their job. Gil likes Enkidu because Enkidu challenges his beliefs and his place as king.

His Noble Phantasm, Azrael, is the only one which can skip an enemy's death. He shares the exact HP values at both minimum and maximum with Kingprotea. He is made obtainable after 'The Old Man of the Mountain' Summoning Campaign. That’s their ideal and it’s an ideal they hold tightly to. 'The Old Man of the Mountain' was available for summoning during the: 'The Old Man of the Mountain' is an NPC only in Camelot, and an NPC-Support only in Babylonia.

Their main goal is saving humanity, but they’re gonna make as many friends as they can on the way and that’s what’s Gil likes about them: going completely out of their way just to be compassionate. In Grand Order, Gil likes Gudao because they’re firmly determined to be /friends/ with people.

But he likes Iskander for chasing his own ideals with a fiery passion he likes Kirei and Arturia because they struggle with their own beliefs and how they clash with those of the people around them he likes Hakuno because she wants to live even though she’s not supposed to. Example: Gil hates Tokiomi who’s after something his family has been searching for across generations but doesn’t seem overly passionate to find he hates Shirou who’s a shadow of his dad’s ideals and a shadow of Gil’s noble phantasm. If they’re someone else’s or you don’t believe in them with the utmost passion, he doesn’t like you. It seems to me Gilgamesh only likes people who are driven by their /own/ ideals.
