- Petra – Thank you for letting me stay.
- Jane – That’s what are sisters for.
- ―Chapter Ninety-One
Petra and Jane start out as friendly until Jane realizes what kind of person Petra really is; cheating on her husband, making nice with Jane to secure a future with Rafael. Once Rafael and Jane become a couple, Petra and Jane are rivals (in Petra's mind, as Rafael has no interest in her), albeit with sobering moments like when Jane comforts a distraught Petra in Chapter Twelve.
Petra and Jane slowly move toward a friendship after Petra's self-insemination and subsequent pregnancy give the pair something real in common. They are presently on very good terms and they often help each other out, sometimes openly and sometimes discreetly.
Jane and Petra find out about each other when Jane is accidentally inseminated with Petra's husband's sperm. It's assumed that Petra doesn't like Jane since she was inseminated instead of Petra. Jane and Petra meet at the hospital when Jane has her first sonogram. Petra hugs Jane and starts to kiss up to her so Jane will give Petra the baby. Jane thinks that Petra is nice and a good person, until Rafael finds out that Petra is cheating on him and tells Jane, which alters Jane's perception of Petra. The two women become rivals when Petra, desperate to force Rafael into giving her more money, tries to make a play on the baby's custody.
Petra invades Jane's appointment with the doctor and insinuates she'll go to court to have the baby since she's still married to Rafael and they allegedly drew up a contract about using a surrogate to have a baby. Rafael decides to hire a PI and finds that Petra isn't who she claims to be, and Petra finally backs off and leaves the couple be. Jane comforts Petra after walking in on her crying due to Miloš returning and telling Petra her mother's not who Petra believes she is. Petra at first rebuffs Jane's attempts to comfort her, but eventually gives in and tells Jane everything about her life so far.
The two have little interaction but are not fighting until Miloš buys Petra a third of The Marbella and Petra uses her leverage to hurt Rafael, who's just lost his father. When Alba remembers that Magda pushed her down the stairs, Jane is livid and insists that Rafael force Petra and Magda out of the hotel by any means necessary. The two have many face-offs, and Jane's malice towards Petra grows.
After Petra finds out that Rafael only pretended to have feelings for her, in order to get Magda jailed for Jane, Petra considers finally moving on but is swayed by Luisa not to. Thinking she still has a chance with Rafael, she self-inseminates and becomes pregnant, discovers that Jane and Rafael broke up only for Rafael to tell her in clear terms that they will never be together. Petra is full of regret, pregnant and, when Milos returns to claim his price for buying Petra into The Marbella, which turns out to be tax cover by marriage, Jane visits Magda in prison for Rafael, and eventually has a small stake in Petra's future not being with a criminal creep.
After realizing she's having twins, Petra asks Jane to help get Magda released from prison early so Petra has some support in her life. Jane agrees and when the two randomly run into each other at The Marbella, they bond bit by bit over motherhood. Jane invites Petra to stay for Thanksgiving at the Villanueva house, which leaves Petra wanting a friendship with Jane and she calls Jane to ask her to lunch. Magda's murdering Ivan gets in the way as she enlists Petra to help bury the body and Petra fakes malice towards Jane in order to derail any suspicion of Magda's criminal activities.
Since Miloš has been imprisoned in Prague, thanks to Magda and Petra's co-operation with the police, Rafael is the person who supports Petra during her pregnancy, and he asks Jane is she will help Petra pick out baby gear, which Jane agrees to, ending up offering to throw Petra's baby shower. The baby research doesn't go well as the two women have very different views on cost and value, leading them to fight. Jane still throws Petra the baby shower, trying to be nice, but Petra is in a late pregnancy no-bull zone. She calls Jane out, saying she'd rather Jane be honest and they finally discover something they have in common.
This truce continues and the two spend time together, resulting in Jane being present when Petra's water breaks and taking her to the hospital. As Rafael is stuck in traffic, Jane stays to support Petra and ends up helping her deliver the twins.
- “That's ridiculous! You always have an opinion and this is the one time I actually want it!”
- —Petra looking for Jane's help[src]
- “I don't care if you don't wanna be in the middle, I need to talk to this over with someone and you're my only real friend!”
- —Petra to Jane[src]
- “You, okay? It's about you because I love you!”
- —Jane to Petra[src]
- Jane is the only person with Petra when she gives birth to the twins, and the first person to hold one of them – Elsa.
- After fighting, Jane and Petra find the one thing they have in common – they appreciate honesty.
- Jane invites Petra to stay for Thanksgiving.
- Jane comforts Petra when she finds her crying in the stairwell.
- Jane and Petra hug when they first meet.
- Petra comforts Jane when she finds out that Xo has a lump in her breast.
- When JR breaks up with Petra, the first person that Petra goes to is Jane.
- It is revealed that Petra and Jane are synced.
- Jane asks Petra to be by her side at her and Rafael's wedding.
- In the end, Jane allows Rafael to have Petra by his side for their wedding given the fact that Jane has a family while Petra is Rafael's only family aside from his sister.
- “It’s almost like they need each other in spite of themselves”
- —Yael Grobglas