Belial's Links
Belial and Asmodeus are best friends. Belial is an older brother figure to Asmodeus, seeing him as his baby brother. Even though Belial isn't always too fond of his perverted nature and lust, he still cares greatly for Asmodeus and will go through great lengths to ensure his success. Asmodeus is one of the only people that Belial trusts.
Asmodeus is best friends with Belial. Even though he has many friends and allies, he holds Belial as his closest confidant since the former demon king also took care of him as an infant. Even though Belial is harsh to him at times, he knows that it is only because Belial actually cares about his wellbeing.
Belial and Zillah are very close to one another. Since Belial and Zillah have a similar taste of humor, their friendship is pretty strong. Zillah was the one that taught Belial everything about Tartarus in order for Belial to be the demon lord as Zillah didn't want to rule the demons. Like Asmodeus and Satan, Belial trusts Zillah with all his problems and rants as Zillah has no reason to tell Lucifer as he is in a "higher" position than him.
Zillah is like a mentor figure to Belial. He was the one that taught Belial everything he needed to know about Tartarus and how to rule the demons. They also get along great as friends due to their similar taste in humor, pessimism, and their strong dislike to angels.
Belial appointed Adramalech to be his chancellor back when Belial was still the Lord of Tartarus. Despite Belial often being frustrated with Adramalech's pompous and conceited attitude, still has a degree of respect for his ally. Since Adramalech has full loyalty to Belial rather than Lucifer, Belial informs Adramalech of many of his plans to get second opinions, much like when Belial used to be the highest lord.
As Adramalech's former boss, the former chancellor has a lot of respect for his previous king. Adramalech enjoys engaging in friendly conversations with Belial. He often tries to tease him as a joke, but it almost always never ends well for Adramalech. Despite Lucifer being the current ruler of Tartarus, Adramalech's full loyalty is for Belial and if he were to ever start a rebellion, Adramalech would side with Belial.