Why Wendy Returns for Season 4 of Sons of Anarchy
Wendy's surprise return in Season 6's Sons of Anarchy after leaving in Season 1 is why she's back in Charming and what happened to her.

Sons of Anarchy saw various characters leave the show for different reasons, but one came back and surprised the audience and the characters: Jax's first wife, Wendy (Drea de Matteo), which is why she returned to Sons of Anarchy . Over the course of seven seasons, the Sons of Anarchy Motorcycle Club has had its fair share of ups and downs, but if that wasn't enough, its vice president and later president, Jax Teller (Charlie Hunnam), has also experienced plenty of problems in his personal life. Of these, the biggest involve his mother Gemma Teller-Morrow (Katie Sagal), his wife Tara Knowles (Maggie Siff) and/or his ex-wife Wendy.
At the beginning of Sons of Anarchy, Wendy and Jax are married and she is pregnant with their son Abel - the problem is that Wendy is also a drug addict and used methamphetamines during her pregnancy. This, combined with Jax's genetic disease, caused Abel to be born with a heart condition, so Gemma threatened Wendy to keep her away from her grandson. Wendy was never seen again after going to rehab, but she made a surprise return in Sons of Anarchy Season 4 as a bigger Show up and stay until the end of the show - but why would she go back to Charming and Jax's life?
Sons of Anarchy: Wendy Returned To Atone For Her Mistakes

Despite Wendy's brief appearance in Sons of Anarchy Season 1, it is clear that she is not the most influential character, and her presence only creates more problems, especially after Abel's birth after. When de Matteo's return to Sons of Anarchy was announced, it was thought that Wendy would come to Charming to cause trouble, especially between Jax and Tara, but her comeback was more about making up for her mistakes and building a relationship with her son contact, and she wasn't even interested in returning to the world of SAMCRO.
In a 2012 interview with EW, de Matteo called Wendy "the healthiest of the bunch" because she returned to Charming after undergoing rehab and becoming a counselor, and in an unexpected turn of events, she ended up being Most consistent guy and SAMCRO around Jax. Wendy wasn't looking for drama, and although she started when she threatened to take Abel away from Jax and Tara because she's now the most stable adult in his life, she ended up getting lost Tara's trust so much that Tara trusted her If anything happens to her, take care of Abel and her son Thomas. Wendy's journey in Sons of Anarchy wasn't easy, and she even had a brief relapse in Season 6, but she certainly did her best to make up for past mistakes and become an important character in Sons of Anarchy.
What Happened To Wendy After Sons of Anarchy

Wendy took care of Abel and Thomas after Tara died and was cleansed again in Sons of Anarchy Season 6, and she slowly but surely gained Jax's trust so much that he eventually told Abel she was his biological Mother. With Wendy the perfect man to raise Abel and Thomas, and knowing his end is near (and he wants his sons to live as far away from outlaw life as possible), Jax convinces Wendy to move in with Nero Padilla (Jimmy Smits) His uncle's farm, take the kids along. Sons of Anarchy creator Kurt Sutter hasn't shared any details about what happened to Wendy after the series ended, so it's understood she and Nero started a new life together, far away from charming and raising Abel and Thomas – and, hopefully, have managed to keep them out of illegal life, As Jax and Tara wished.