The last episode as a whole, especially near the end.
At the end of "No Mass," Lydia shows her acceptance of Penelope drawing strength from things other than religion by hanging a picture of Serena Williams, Penelope's inspiration, on the fridge next to her picture of the Pope.
Penelope finding help and solace in the women's veterans group. She gets to open up about everything she has been holding to people who share her views and understand what she's been through.
Alex is the first person Elena comes out to, entirely by accident. He promises not to tell, and means it (he lets it slip to Schneider, but it was an honest accident, and Schneider keeps his mouth shut at Alex's request), and is completely cool with it, albeit a little surprised.
When Elena comes out to her, Penelope has only one problem: she's frustrated with herself for not being 100% okay with a lesbian daughter. That's how much she cares about supporting Elena's identity and sexuality.
Lydia at first has a problem with it due to her religious beliefs... until she thinks out loud for ten seconds and talks herself around.
Lydia: You have to understand: I am a religious woman. And Im sorry—Im sorry, but I have a problem with Elena being gay. It goes against God! Although, God did make us in his image. And God doesnt make mistakes (gestures to herself) clearly. And when it comes to the gays, the Pope did say, Who am I to judge? And the Pope represents God. So, what, am I going to go against the pope and God? Who the hell do I think I am? Okay! Okay, Im good. So, when is the parade?
And when Penelope questions how quickly she turned around, Lydia responds that Elena is her granddaughter and she will love her no matter what.
Lydia admitting that opening up feels good when she finally tells Penelope the story about her late sister Blanca. Since Penelope never even knew about Blanca, this the first time Lydia opened up about her in decades.
When Victor bails on the father-daughter dance, Penelope, Lydia, Alex, Schneider, and Dr. Berkowitz all go up to dance with Elena instead. As a family.
Lydia has been trying throughout the entire episode to make a dress for Elena that will give her a happy Tearjerker moment, yet she simply "likes" all the alterations. What finally gets Lydia her reaction? A white suit instead of a dress.
The fact that Josh, an extremely popular boy at Elena's school, genuinely has a crush on her. And when she tells him she's gay, he's still her friend, and is happy to escort her at her quinces. What a nice kid.
Schneider and Lydia secretly working together to get Carmen, Elena's best friend, at her quinces. Elena's completely overjoyed to see her.
Elena getting together with Syd, and Penelope supporting it.
Lydia trying to help Elena flirt and find love.
Even though they don't really get it, Penelope and Lydia both respect Elena's non-binary friends, and just roll with the "pronouns" business, despite their confusion.
Syd and Elena's Big Damn Kiss in "Locked Down." Or, rather, Big Damn Kisses.
Penelope apologizes to Schneider for her depression-fueled cruel remarks towards him. He instantly forgives her, giving her a big hug and saying, "Ah, I can take it. We're best friends."
Lydia finally overcoming her anti-medication stance, and supporting Penelope's decision to go back on her meds and return to therapy.
Before that, Lydia in Confession, telling the priest she wishes she could take Penelope's pain onto herself, so Penelope wouldn't have to hurt.
Alex speaking to a comatose Lydia, doing her nails and chatting about everything that's happened while she was out.
Alex:(smiling) I know you'll wake up soon.
From the same episode, Dr. Berkowitz at Lydia's bedside, telling her he understands and accepts the fact that Lydia will always love Berto, and that's okay. Because he loves her too much to let go of what they have, be it friendship or something more. He even calls her the love of his life, and confesses that Lydia is the first thing that's made him genuinely happy.
Also in "Not Yet", when Lydia's talking to Berto in her close to death experience and he asks her if it's time, Lydia looks over at Penelope, who's curled up and asleep next to Lydia on her bedside, and tells him "not yet". The statement is greeted with thunderous applause and cheering from the audience.
Much like how he was the one to get through to her in "Hello, Penelope", when Penelope is dealing with anxiety attacks, her go-to coping method is to text Schneider, who texts her pictures of dogs in wigs to distract her until she's calmed down and then coming down to check on her and make sure she's okay before hugging her.
Victor shows just how much he's learned his lesson by inviting Elena to be his Best Woman at his next wedding, complete with tuxedo, and formally apologizes to her in front of the whole family, after which they finally get their dance.
Schneider and Dr. Berkowitz bonding in "Hermanos." Both ending up in the Alvarez apartment while the family are on vacation, they have dinner together, and later sit on the fire escape and talk. Dr. B even tells Schneider he's proud of him for achieving eight years of sobriety, which Schneider admits he's never even heard from his own father. Likewise, Dr. B is touched when Schneider calls him a father figure, admitting that it's the complete opposite of how his grown biological children see him.
Penelope and her brother Tito reconciling after she calls him out for not visiting Lydia in the hospital and gets him to realize that running away from family tragedy isn't something that he can do forever. Later on, Tito apologizes to Lydia for acting selfishly.
When Victor comes for a visit, Lydia assures Elena she's on her side, and prepared to flip a table if Victor does or says anything to upset her again.
Penelope is jarred meeting Victor's new fiancee, Nicole, who's a very Suspiciously Similar Substitute to her. She wants to warn Nicole of the kind of person Victor is while at a bar. Nicole reveals that Victor told her all about the horrible stuff he did and that it was Penelope "being strong enough to leave him" that pushed Victor to clean up his act. She knows Victor can be tough but she still loves him. Penelope realizes the two have a lot more in common than just looks and they become friends.
Dr. Berkowitz volunteers to teach Elena how to drive, and the two unexpectedly bond over common music tastes ("Sapphic folk is my jam!"). When finding out just how bad his relationship with his daughter is, Elena secretly drives him to her house so they can talk face-to-face. It's clear they've still got a long way to go, but thanks to Elena giving that nudge, the ball has at least started rolling.
At the end of the season, Dr. Berkowitz offers to take Lydia to Miami so she can spread Berto's ashes, since that's as close as she can get to Cuba. Then, in the very last scene of the season, we find out he did even better than that: they actually went to Cuba. Regardless of the fallout that will probably occur, it's hard not to feel happy that Lydia is finally in her beloved homeland again.
After a big fight on Valentines Day, Elena makes it up to Syd with a homemade card of a heart surrounded by ones and zeroes, made of the other numbers, ie a non-binary heart. Syd is so moved that they blurt out the L word.