Lubbock has known Najenda since his childhood and military days. He tends to call her Ms. Najenda. While he is in love with her, she doesn't seem to respond to or notice his feelings for her. In Lubbock's last moments he thought of her.
Lubbock is often caught trying to peep on Leone while she is bathing. Most of his attempts end with him being beaten up by Leone herself.
Lubbock considers Susanoo a rival for Najenda's affections, since he is her Teigu. As a result he has an inferiority complex, becoming irate any time Susanoo does anything impressive. He considers Susanoo to have stolen his position as the lady killer from him, though Mine states that he has "always held [his] current gag position."
Lubbock has a comical relationship/friendship with Tatsumi while he was however worried when Tatsumi was kidnapped by Esdeath even though he did not state it, and had also once talked him into using Incursio to sneak up on and scare Chelsea, while she was bathing, so he could assess the danger for himself before trying to peek at her while she bathed.
Black Star and Lubbock are friends (from Underground) and get along pretty well with each other. But if somebody is cooler than Black Star, Lubbock is on their side rather than on Black Star's.
In Legends of the Multi-Universe: Armageddon, like the Underground members, he learns White Star is Black Star's father and one of major threats in Gotham. He didn't learn about him until LOTM: Weirdmageddon when White Star joins the Underground.
Lubbock and White Star's relationships is more than just poor. After hearing White Star trash talk about females and beats them for no apparent reason, Lubbock is horrified about White Star's relationships with women and fears of what White Star is going to do to Black Star.