Plasma's Links
Close friends. She cares for like a sister she never had. Blood had no reason to allow her into her home, (feed her and allowed her a room to rest) She feel indebted to her. She will be her sword and shield.
Close friends
Even with Pulse using her for protecting his sister, she still considering him a friend. He took her into his Clan. (after his sister insistence)
Plasma is as close to a friend as he can get while he uses her. While yes she is Head of House, she makes a great bodyguard for his sister. Plus with her skills in stealth she make a wonderful spy when he force to host galas/parties.
Trying to help him work through his feeling with Blood. Though she has threating him if he hurt her, She'll help Pulse end him. Regardless he helps her with her questioning taste in crushes.
While he grateful for help in his emotional turmoil regarding his feeling for Blood, he could do without the threats. In return he helps her (usually a drinking buddy that is an ear to her venting) feeling with Delilah.
Plasma feels sorry for Delilah as she watches this girl being used and manipulated by Pulse. It doesn't help that she herself has a massive crush on Delilah and is jealous of the man. Though given what she has seen when she is interacting with her, trying to use her for information, she is questioning her taste in women.
Delilah is jealous of this woman for being close to her man. She believes that Plasma is also using Blood to get to Pulse (like how she did). So she decides to flirt and use her for information (albeit terribly). She ironically doesn't notice that she is doing the same thing that she fails to notice Pulse is doing to her.