İlkay appears to have some great sense of loyalty towards Zaganos, making it his ultimate purpose during the war with Balt-Rhein to protect him. He also proved to be ready to threaten people with a higher standing than him, such as Mahmut, in Zaganos' favour. What kind of relationship the two have outside of their professional is uncertain, although it appears as if İlkay trusts him a lot and he is commonly seen by his side.
Just what kind of relationship the two have seems very uncertain, though judging from their interaction in chapter 78, they appear to be on friendly terms. İlkay also seems to acknowledge that he's a great warrior but also adds that he has always wanted to see Cemil fall, making it uncertain just what kind of relationship the two have.