Leto Atreides II: Nephew
Alia cared for Leto, even though because of her possession that she could not show it. She would try to give him advice, although the advice she gave didn't suit the situation very well. Her possession led her to be suspicous of everything, and she tried to let Leto be aware of such suspicions so he wouldn't get hurt.
Ghanima Atreides: Niece
Alia's love for Leto was a much as her love for Ghanima. She would also give advice to her to try and protect herself. Although we don't see much interaction, it is clear that Alia has feelings for her niece.
Paul Muad' Dib Atreides: Brother
Alia always looked up to Paul, and even so, Paul would seek out Alia's advice. Even as a child she need the reasurrance of her older brother and always wanted him close by. She somehow felt that he could understand her and didn't see her as someone diffrent. Even as an adult she took Pauls examples and learned his ways. She carried on his legacy once he went off into the desert. She knew very well what he wanted to accomplish, yet, she pretended to not know what destruction it could bring. She still tried to bring the greening of the desert. At her death, her last words were "I want my brother". Perhaps because he was gone, she had no one to look to and because she was ruling an Empire alone. All of these struggles led her to the trial of the abomination.
Reverend Mother Lady Jessica: Mother
It was clear that Alia had feelings for her mother, although they were not very strong ones. Alia had feared that her mother had returned to Arrakis as a Bene Gesserit, not as her mother. Alia believed that Jessica would expose the twins and herself for being preborn, and worst of, end her reign of power. Alia also disliked her mother because she was the one who awaken her to consciousness before birth, because of her mother, Alia was an abomination.
Duncan Idaho: Husband
Alia loved Duncan very much. Although as possession became worse, her love had almost withered away for him. But deep down in her heart, she loved him more than ever.
Baron Vladimir Harkonnen : Grandfather
Alia was the one responsible for her grandfathers's death. Although his spirt was inside Alia, and he found a way to possess her and once again tried to regain ultimate power for himself. Although to Alia, she thought his motives were for her, she agreed to help her rid away the other spirts. Eventually, she realizes the Baron's true intentions, but she acted too late as she was already under possession.