While battling villains with super strength, shape-shifting ability or an affinity for lethal toys is no walk in the park, the toughest fights are always with those we love. Whether it’s with a family member or a friend, the people we trust and care for always do the most damage when they’re angry. But equally as hard is what we do to them. Things we may say in the heat of the moment, or things we must do that are unpleasant, but necessary, may haunt us for days, weeks and even years afterwards. Even the strongest superpowers are no help with overcoming it.

Tonight’s Supergirl, “In Search of Lost Time,” continues last week’s focus on personal struggles. But where the prior episode looked at Winn’s relationship with his mother while the team fought a super-villain who had been inspired by Winn’s newly deceased father, this week cuts closer still, as J’onn J’onzz and his father M’yrnn find themselves struggling to accept and contain M’yrnn’s newly discovered mental deterioration.

“Even though M’yrnn was in prison, he had his mind and the freedom to go through the centuries in his mind,” explains Supergirl Executive Producer Robert Rovner. “We make the parallel that it’s kind of like taking away your car keys. You’re more reliant on somebody than you’ve ever been before. What does that do to you emotionally as you feel like your independence is taken away?”

The real-world analog, as anyone who’s been impacted by Alzheimer’s or any other form of dementia can tell you, is clear as day, and as a result, many viewers may find M’yrnn and J’onn’s struggle instantly—and perhaps a little painfully—relatable. But if watching a one-hour, weepie drama where a beloved character slowly loses sense of who he is sounds too heavy and real for you, don’t worry. Supergirl is still a sci-fi show, and unlike the human equivalent, M’yrnn’s struggle comes with some powerful otherworldly side effects that impact the rest of the characters.

“What I love about this show is that I think it’s kind of subversive and sneaky,” reveals actor Carl Lumbly, who plays M’yrnn on Supergirl. “It enables you to think about things without necessarily feeling like you’re being lectured. In terms of playing it, however, it does tap into experiences I’ve had.”

Lumbly has had experience as a caregiver, something that he channeled while preparing for tonight’s emotional episode, bringing a sense of honesty and truth to what takes place on screen.

“I had a situation,” he shares. “My late wife had a number of cancers, so I took certain steps to be present . Not necessarily because there was a date certain, but because every day was precious, and every day held the possibility that the situation could be turned around. It’s not unusual. Some people have it with a parent who doesn’t know you one morning. I don’t know how you can rate those experiences because that one would be stunning for me.”

They’re experiences that many on the Supergirl creative team might have some familiarity with. As Rovner explains, “A lot of us in the writers room have dealt with dementia in our own lives, and so we wanted to make this story very relatable. M’yrnn will be facing circumstances that we feel a lot of children and their parents go through in this journey together. One of the things that I think is beautiful about the story of J’onn and M’yrnn is that through the rest of the season, M’yrnn and the way he copes with this, and the way J’onn helps him, will have a profound effect on J’onn. So, I think even though their time together might be shorter than they had hoped it would be, it will really forever change both of their lives and their perspectives about things. It’s a very emotional journey that they’re taking together.”

And not just for them. Those side effects we mentioned earlier? Turns out they bring out some pretty bad behavior in anyone within close proximity to M’yrnn, including Kara and Mon-El, who wind up airing a few grievances of their own.

“The way that their relationship ended last season, they never really had a chance to break up,” Rovner elaborates. “Things that might have been said under other circumstances, they didn’t have the opportunity to say. We all felt that it was important for Kara to really get everything off her chest for them to move forward with a new friendship, on a clean slate. This episode was allowing us to do that—to kind of let everything be said that needed to be said so that they can finally move forward.”

But that doesn’t happen without a few bruises—both emotional and physical. In fact, things get so bad that the entire D.E.O. is affected, and with Supergirl impacted, it’ll fall on Martian Manhunter himself to sort things out. The problem is that it’s M’yrnn and his deteriorating mind at the root of the problem, putting J’onn in the unenviable position of having to confront his own ailing father.

“I think there’s a villain inside us as humans, and I think that’s what the episode was for me,” says Lumbly. “A definition I once heard was that people aren’t necessarily so much evil as they are overwhelmingly self-interested: ‘I didn’t mean to run you over, but that was the last Apple Watch. In going for it, I might have tumbled a few people. My intent was not necessarily evil, but I didn’t check my impulses.’”

“For M’yrnn, it’s finally seeing what’s happening and being cognizant of that, and that he needs to accept the help of his son,” reveals Rovner. “That’s his epiphany in the episode, and for J’onn, as well. He loves his father very much and he doesn’t want to see him go down this road. He’s just gotten him back, so he doesn’t want to face it either.”

For any fans who might find themselves sharing that sentiment, don’t worry. While “In Search of Lost Time” is a powerful, important episode that stands out as one of the strongest this season, Supergirl will be returning to her search for the Worldkillers very soon.

“Much of the rest of the season deals with the Worldkillers and Reign,” Rovner says. “What we saw in one of the previous episodes is…how do you save the world when saving the world means saving your friend? Sam and Reign are inextricably linked. They’re working hard to keep everybody safe and find a solution to that, which will take them in very exciting, different directions.”

Plus, both Lumbly and Rovner promise that while M’yrnn’s path on the show may have taken a sad turn, the character will still offer plenty of his now beloved humor.

“I think I’m incredibly funny, and I think M’yrnn does too,” chuckles Lumbly. “I’m not necessarily thought of as a funny person. In my work and career, I’ve been thought of as sort of serious and dour, and people who know me laugh because I’m a little bit of a wacko.”

“The story, even though it’s very emotional, it’s like real life,” adds Rovner “Even in the darkness, there are moments of levity. We feel blessed to have Carl on the show. He is so funny. In the same episode, we’ll laugh with him and then we’ll cry for him. We won’t lose any of either side of that.”

"In Search of Lost Time" airs tonight on Supergirl at 8 p.m. (7 p.m. CST) on The CW. Be sure to stop by after it airs to read Tamara Brooks's thoughts on it in the #DCTV Couch Club!