After that whole mess with Frieza, Cell decided to squeeze mind training into his schedule. Absorbing the tyrant was a smart move that increased his strength and may allow him to grow faster, but it may have some consequences, like a shorter temper or something. And, this ends up helping to prevent that. Plus other things. Instead of getting reckless when he's forced into a corner, he'll likely just try to find his best way out of it, using his multiple techniques, or just any superior quality or trait that he has. Also, because of this, he decides not to join in the tournament against Universe 6. No matter what Beerus did to try and make him, even threatening to destroy him, Once Cell makes up his mind, there's barely ever a way to change it. Anyways, Frieza problems are solved for now.

Now, back to the arc.. One day, Cell is in the arctic as always. Destroying Glaciers with single punches, melting the area around him with explosions of ki, things like that.

"Living in the arctic is boring and lonely. I may ask Bulma for a mansion."

Suddenly, Cell gets a call from the woman he just mentioned. Oh yeah, he doesn't know why he needs one, but Cell has a phone now, by Gohan's request.

"I'm in the middle of training, lady. This better be good."

And of course, it was. Apparently, that boy Trunks was back from that future timeline. Damn, Cell settles on training 3 brats and a 4th one shows up. Oh well, guess it would be best if he just got there. So, he does, with the help of Instant Transmission.

"Alright, what happened in the future to make him crawl back here this time?"

He asked. Bulma just told him they didn't know. He fell unconscious the moment he got here, apparently. Either way, he was gonna have to do something about him depending on these fools instead of himself.

Anyways, Trunks begins to wake up after things play out a bit like canon. The first person he has his sights on is Cell.

"I thought Gohan killed you.. You BASTARD!"

He tries to land a very weak punch on the Bio Machine, but just like Goku, he simply lifts a hand and catches it.

"Save your breath for telling your new tale, I'm not the enemy anymore."

Trunks doesn't want to at first, because, well, it's Cell. But he does so. The boy from the future explains what's going on in his future world, and evil Goku, the death of his mother, things like that. Cell's first comment is-

"I could've done better."

Nobody pays attention to him. But he knows they heard him, so he keeps his cool.

So, let's skip to when Goku Black arrives in the past. Goku is the first one up there, ready to fight him- But Cell decides to step in, going up there and telling Goku to stand down.

"Oh, come on, Cell! It's not every day that you get to fight yourself."

Cell simply tells him-

"I didn't participate in that silly tournament, which apparently had lots of skilled fighters. I missed out on that, but I'm not missing out on this."

Goku simply shrugs and descends back down to the Earth. Guess now is Cell's time to shine. The fight starts off slow, But quickly picks up speed.

"So, creature, what are you supposed to be? I didn't see you in the future at all."

The imposter asks the perfect being. This was a rather easy question.

"I'm a Bio Android, made from the DNA of.. Pretty much everyone down there. I come from that time, but I decided to settle here because it's less destroyed."

He explains. But less talking, more fighting. Cell decides to get a good amount of damage in, waiting for the fake Goku to throw a punch, just to grab their wrist and yank him to his left. Then, the Bio Android's left knee shoots up and gets a perfect shot to the stomach. Black coughs up a little blood, but Cell isn't done. He puts his hands together, and throwing them down as hard as he can, does some major damage to the counterfeit's back, as they quickly plummet to the ground below. Cell uses Instant Transmission and appears just a few yards away from where he landed. Black slowly gets back to his feet, for some reason, laughing.

"This damage, this pain.. It will make me stronger!"

And with that, he activates his Black and Purple aura. He was right, that power of his was growing. Cell could tell. But, doesn't say anything about it just yet.

"Tch, masochists.."

Cell powers up and activates his aura as well. Just like a Super Saiyan 2's aura, yet his power is nearly on par with a Super Saiyan Blue's.

They trade blows for about 10 seconds, but then Cell lands a Right hook. And another one. He kept hitting Black in the face with that right fist, just like he did Goku back in the Cell Games. Yep. The fight was one-sided now. But suddenly, Black's body moves against his will, getting pulled backwards, it seems Time is correcting itself. Suddenly, knowing he has to finish the fight quickly, Cell shows off his Frieza.

"If pain makes you stronger, then I'll make you GODLY for the next time we meet!"

Cell shoots over to him, landing a massive Left Punch that breaks Black's nose. Then a kick to obliterate the ribs, then finally, an elbow to the gut that knocks the wind out of him and sends him back to the future. The one with Goku's appearance didn't even have time to destroy the Time Machine.

Cell takes a long sigh, before powering down and flying back over to the others.

"Well, that was something.."