In a nutshell, these two seem to somehow balance each other out and be worthy adversaries, but are incredibly antagonistic toward one another. After conspiring to keep Jane and Rafael apart (and failing), they resume being antagonistic towards each other, mostly on Michael's part, the reason for this being unclear, thought it could be misdirected anger at himself for ever teaming up with Petra in the first place. Michael seems to think very little of Petra, but she doesn't let him sit on his invisible high horse as she points out his hypocrisy, as she knows what he is capable of in turn. After Michael wins Jane back, he settles down a bit, although the two of them never become friends. Petra attends their wedding and sees Michael sporadically, mostly in conjunction with Jane and Rafael. After Michael dies, Petra is there for Jane and, together with Rafael and the three kids, they all become a family. When Michael returns Petra's her trademark socially awkwardly formally presentable around him, which is her trying to be encouraging that he's not dead. She does, however, let Michael live at The Marbella, both before and following him retrieving his memories.
Petra and Michael first meet at the first sonogram. Michael already knows Petra as the cheating wife of Rafael, which, spiked by his jealousy, Michael decides to utilise. Almost immediately, after being ushered from the room and left to watch Jane and Rafael experience the scan, they strike up an alliance. Petra wants to stay with Rafael, even if it means raising his and Jane's child – Michael doesn't want the baby. However, things get complicated when Zaz is murdered and Petra is suspected complicit. Michael helps her remove crime scene evidence to avoid her arrest, which could lead to Jane wanting the baby herself. Later on, Petra threatens that she'll tell of his actions if she is arrested, leading Michael to compromise his own investigation.
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