Supergirl faces an old enemy this week in “We Can Be Heroes.†But not all is as it seems. Livewire is back, and she’s as fierce as ever. Kara gets a new ally in Mon-El, and the Guardian is finally unmasked.
Mon-El gets to train with Supergirl, and he’s almost ready to become a superhero. Kara reminds him that the number one rule as heroes: Protect the people. Kara is still nervous about Mon-El going out into the real world, but she agrees to let him come when news of Livewire breaking out of prison reaches the DEO. When they search out Kara’s nemesis, they instead find two Livewire wannabes. It’s a good thing Guardian shows up to help keep the civilians safe. Mon-El is struggling with keeping Kara safe and protecting the people. Unfortunately, Guardian gets knocked out, which allows Kara to finally unmask him.
Kara, James, and Mon-El are all in this weird relationship triangle. Everyone wants to be a hero, but no one approves of the other. Kara thinks that Mon-El can be a hero, but he’s not ready. Kara thinks that James should not be out there fighting crime; she only sees that he will get himself hurt. Mon-El tries to be the mediator, hoping that everyone can just fight together. No one can seem to shift their perspective.

James says that Mon-El isn’t a hero, but Kara asks why he gets to decide that. Then, she can’t see her own argument when she says that James can’t be a hero. James tries to explain that what he was doing before wasn’t enough, but this is. He was never meant to be Superman’s shadow, or Supergirl’s. Kara only sees that James is human and is going to get himself killed. You know who else is human, her sister Alex. Kara and James have a very heated exchange, and I’m not sure how their friendship will survive this.
“You are never going to be strong enough for this,†Kara tells James
“Who are you to tell me how to be or who to be… I am meant for this,†says James.
“If you don’t stop, I’ll stop you,†says Kara.
“You’re welcome to try,†replies James.
Now that none of them can work together, Winn tracks Livewire but doesn’t tell anyone except James. Mon-El overhears and wants to be the hero for Kara. Of course, Mon-El and Guardian get tied up and have to let Kara save the day. Kara realizes that she was wrong about Livewire when they discover that Livewire was being used as an experiment. Kara ends up letting Livewire go but warns her that she’ll be there to put her away should Livewire hurt anyone else again.

In the end, Mon-El finally admits to Kara why he is working with her. He seems to somewhat hear the calling to be a hero. Mostly, he feels like he should be a hero since he has powers. The other reason he wants to be a hero is to be closer to Kara. He admits that he remembers kissing her while he was dying. He felt that he was okay with dying because at least he got to kiss her. He tells Kara that he knows she doesn’t feel the same, and it’s okay. He just wants to keep working with her and put this behind them. Kara just thanks him for being honest; cue the collective groan here.
Meanwhile, M’gann is still locked up at the DEO. She starts hearing things, and then she busts out of the cage. She faints and stays unconscious. Alex analyzes her and realizes that her vitals are normal. They have no idea what’s wrong with her. As far as they can tell, she’s dying, but there’s no way to tell how. She only has a few hours left before she’s dead; J’onn has to do something and fast.
The only way for J’onn to help M’gann is to merge their minds. He could see inside her head and find out what’s happening. At first, J’onn is appalled. He won’t give her his people’s memories; he won’t give her his daughters’ smiles. J’onn doesn’t believe she deserves that as a White Martian. With M’gann close to death, J’onn decides to do the right thing and try the bond. He’s sees her memories of the last days on Mars. She was supposed to kill a Green Martian, a little boy. She refused and let him run; she killed her own kind to do what she could to save the Green Martians. M’gann explains that she only ever wanted to be his friend, to make J’onn feel less alone. J’onn forgives her, and M’gann is able to regain consciousness.