Thor Odinson - Initially, Thor and Bill were briefly enemies, though that was more or less due to a huge misunderstanding. It's clear that Bill admired the god's valor and strength after saving him at Skartheheim, rather than allowing him to die in the sea of lava. Since then, Thor has considered Bill to be an 'oathbrother' and also an honorary Asgardian. His trust of Bill is apparent in that he himself gave Bill control of the Asgardian army during Ragnarok while he was away, and he even spared his life before Asgard could fall.
However, at least on one occasion, Bill had to fight Thor again -when he [Thor] had 'warrior's madness'.
Lady Sif - Arguably Bill's closest companion for some time, Sif saw past Bill's monstrous appearance and saw in him a spirit whom she became attracted to (as at the time, she was disillusioned with Thor and their relationship had temporarily ended due to other factors) in more ways than one. She even accompanied him after he left, even while trapped on Earth for a good deal of time. She respects him as a warrior and values him as a close companion and confidant.
Although they were never officially in a relationship, it is still clear that Bill too cares deeply for Sif, but whether or not they will meet again -especially with Thor now showing a great deal of concern for his missing fiancee- and if she still has feelings for Bill remains in question.
Thor Odinson - Initially, Thor and Bill were briefly enemies, though that was more or less due to a huge misunderstanding. It's clear that Bill admired the god's valor and strength after saving him at Skartheheim, rather than allowing him to die in the sea of lava. Since then, Thor has considered Bill to be an 'oathbrother' and also an honorary Asgardian. His trust of Bill is apparent in that he himself gave Bill control of the Asgardian army during Ragnarok while he was away, and he even spared his life before Asgard could fall.
Lady Sif - Arguably Bill's closest companion for some time, Sif saw past Bill's monstrous appearance and saw in him a spirit whom she became attracted to (as at the time, she was disillusioned with Thor and their relationship had temporarily ended due to other factors) in more ways than one. She even accompanied him after he left, even while trapped on Earth for a good deal of time. She respects him as a warrior and values him as a close companion and confidant.