Why Would He Have Sex With Her + Why Would She Not Kill Him ?
I honestly don't get why he would have sex with her considering what she just did she managed to literally transport from her cave miles away in a second almost like teleporting and manages to kill all of his men in a second and hang all there corpses from the ceiling inches from where beowulf is sleeping all without waking him up so she is like ultra dangerous yet he wants to have sex with her why would you do this like him putting his guard down when she could snap and kill him in any second ?
Yes I get that she is stunning and ultimate seduction but considering what she just did also i get that Beowulf was just way over his head he saw no weapons affected her she was like a ghost with the sword going through her and the power she demonstrated at the end of the day she is a demon and he no matter how strong is still just a man and no man can kill her which is why the king knew that beowulf had failed and if beowulf could not kill her no one could so he killed himself.
Also she only did not kill him because she wanted a son and in some twisted demon way she saw him as the ultimate man and wanted a child like that and wat way to get back at your enermy than to have his child and then use it against him someday but still with all that anger over the death of her son and the sudden change in personalty was a bit exaggerated and after he did the deed why not kill him then with the power she had surely it could have been done in a second.