"They demand a presence when they walk in the room," Souza told Living. "And it's invigorating to feel on yours toes all the time.
"But work-wise, they're people we obviously admire a lot. And I feel like having them on board does definitely make us up the game as well.
"But I don't feel like it's done in a pre-fabricated way. I feel like we have so much to learn from them and we admire them so much.
"It's not like they impose it. It's just naturally there. You can't teach someone how to have the presence that they both have."
British actor Enoch, recognisable to Harry Potter fans as perennial Hogwarts presence Dean Thomas in all but one of the eight films, was also able to draw on his own life to play the often overwhelmed Wes.
"It certainly gave me a point of reference from that perspective.
"I arrived to shoot the pilot in Philly and it was completely new to me. It was nice having that mirror.
"And it was, to some degree, amusing to me to see that. But the real attraction is the sophistication and the depth of the work."
Souza, who previously found success as an actress in her native Mexico, jumped at the chance to personalise her character.
"The character I'm portraying is kind of like the third-row kind of girl and she's not the first one to speak up. She's sort of the observer.
"Her name was Laurel Wilding, and Pete [Nowalk, show creator] and the team asked me if I wanted to change the last name to be Latin.
"I was surprised they even asked me. And I loved that they were caring about who we were as actors and what we could bring to the table.
"So I remember Pete saying, 'You speak French and you're Mexican, but you lived in Colorado. We want you to bring it into the character.'
"So I was honoured and grateful. I don't know if it's going to be the Latina you're used to seeing on TV, because I feel like there's a strong stereotype out there, and I'm happy to show a different side to that."
Beyond the central serialised murder-mystery involving the students, a lot of How To Get Away With Murder's drama comes from the murky ethical waters the students must wade into to keep up with Davis' legal eagle.
"My character certainly is a newcomer to this environment, as we all are," says Enoch.
"But Wes is much less uncompromising at the start, so he has those reservations. [With Annalise], I think that's to do with understanding law and understanding the grey areas and complexity of it.
"You can't always come down with a very neat, pre-prepared notion of what is acceptable and what isn't. I think that's what we need to find out. That journey is part of it for me."
How To Get Away With Murder premieres Tuesday at 8.30pm on TV2.