Despite Endeavor's temper tantrums, Hawks does never seem to be scared of him. Endeavor calls him "little brat" which implies he still thinks of Hawks as very young. Hawks appears to have been a fan of Endeavor ever since he was a kid. It is shown that Hawks once was in possession of an Endeavor plushie, although it is unclear whether Hawks owned it only because of its low price. Hawks favored Endeavor because he challenged All Might when no one else would truly try to overcome him.
The two get along well despite Endeavor's brusque attitude and Hawks' constant banter. Hawks even requested a team-up with Endeavor as he needed his help in investigating concerning sightings of Nomu.
Endeavor and Hawks fought together until death against Hood and won only due to a combo attack. Endeavor is easily provoked by Hawks, but also shows slight affection to him. He even appears solicitous when he tells Hawks he should ask for help and not to expose himself to any greater danger.
Hawks felt guilty because of the scar that Endeavor received on his face, although he could hide his sorrow. Endeavor knows Hawks attitude and facial expressions very well, even to the point were he was able to decipher Hawks nonverbal warning.
They appear familiar with each other, as Hawks visited him after the Kamino Incident. It is implied Hawks was responsible for Tsunagu's disappearance.
Paranormal Liberation Front
Dabi is the first one Hawks has contacted in the League of Villains and the first person, to make Hawks losing his nonchalant behaviour for a moment. After the incident with Hood, Dabi was confronted by Hawks asking why he broke their promise on the Nomu that was supposed to show up. While doing this, Hawks threatened Dabi by holding one of his feathers close to his face. Hawks was disgusted at having to deal with Dabi as seen when he walked alone, but towards Dabi he keeps a friendly and serene facade.
Hawks knows Dabi wants to use him and is aware of Dabi's distrust. He allows Dabi to take advantage of him and plays the fool in order to let Dabi forget about the risks and to steer Dabi's focus on the returns. When Hawks offers Best Jeanist, he gains more of Dabi's trust. Not because Dabi completely believes in the credibility of the corpse, but because he sees Hawks being able to commit a murder. Dabi is counting on Hawks' "dark side", the hidden part of his personality able to kill in favour of his goals.
As Hawks enters the inner circle of the Paranormal Liberation Front, Dabi states to Hawks that he "looks happy". He subliminally states that he is still observing the hero. Dabi enters Hawks personal space, which implies Dabi’s gesture being a display of dominance. Their relationship is based on mutual exploitation.
Hawks would put up the façade of being a loyal soldier by reporting about Endeavor's activities.  He also pretends to be fanatic by reading one of Destro's liberation books and passing them out to heroes, something Re-Destro thanked him for. However, it is revealed Hawks was sending his fellow heroes messages about Re-Destro's organization.
Hawks helps Twice to understand more complex themes about Destro's ideology, supports him and gives him friendly tips as to how to speak to his soldiers. Hawks opens up about the feeling of being trapped in the hero system, without really belonging anywhere and manipulates Twice into emphasizing with him.
Hawks recognizes Twice mental ideals as "kind-hearted", but nevertheless as a weakness to exploit. He filters relevant information from their conversations. Twice wishes he could "get rid of these bugs" on Hawks' wings and shows multiple times how much he trusts the winged hero. He states that Hawks "can't be a bad guy" and wants to free him from the hero society. Hawks doesn't seem to enjoy manipulating Twice, but he shows no signs of quitting.
Hawks admitted he took in Fumikage mostly because he wanted information about the League of Villains. The first time they had met, Fumikage could not keep up with Hawks. The heroes that worked with him told Fumikage that Hawks was just too fast and they would usually deal with the aftermaths of Hawks fights. But Fumikage gained Hawks favor due to the amount of potential he had.
After the work studies, Hawks once again asked for Fumikage during the Shie Hassaikai Arc as they trained together. It's shown that Hawks is surprised on how Fumikage keeps up with him during patrolling. After the patrol, Hawks takes Tokoyami on a flight to show him how much potential he's wasting. With the help of Hawks, Fumikage devises a new move named Black Fallen Angel.
Hawks likes to joke about them both being birds and stated he is happy Fumikage being the one who came.