Because Philip is the only living child of Victor, he stands to inherit the Kiriakis empire.
After coming to Salem in 1992, Vivian met and fell in love with Philip Kiriakis' father.
The two eventually got married, but their relationship didn’t last long.

Victor found himself drawn to Kate during his marriage.
After falling hard, he opted to leave his wife to pursue a romance with her.
Of course, Vivian was furious about Victor’s betrayal and looked to get revenge.

When they couldn’t do so naturally, they turned to doctors for help.
However, Vivian found a way to ruin it for the couple.
Instead of Kate being implanted with the embryo, it was implanted in Vivian instead (viaSoaps).

Vivian hoped that carrying Victor’s child would convince him to grow closer to her.