The last we saw Harrison, his father was abandoning him in the 2013 series finale.
ENTERTAINMENT WEEKLY Were you aDexterfan?
JACK ALCOTT: I had never watched an episode of it.

Jack Alcott.Peter Mellekas
I had friends and family members who loved it, but I had never watched a single episode.
I barely knew anything about it.
I was like, dude … blood …. kills people.

Jack Alcott and Michael C. Hall in ‘Dexter: New Blood’.Seacia Pavao/SHOWTIME
That was literally all I knew.
My character was named Randall through almost all of the auditions.
That was all I knew up until my chemistry read with Michael C. Hall.
Then I was like, “oh my gosh, holy crap.”
Then I signed an NDA and they sent me another scene where my name was no longer Randall.
I did a little bit of research and realized I’m his son.
I was like, “I’m so sorry.
I’ve only watched the first season.
He was like, “Do not do that, dude.
You’re Dexter’s son.
I’m assuming that Harrison isn’t too happy with his dad these days.
It’s been a long time and I haven’t seen him and I’ve been looking for him.
What I can say is that Harrison has had a really rough time for the past eight years.
Like, it’s not been great.
He learns that his dad is not dead and goes to find him.
It’s me following him, trying to confirm his identity.
I’m finally able to see him and confront him.
It’s just a heartbreaking scene and a really fun one to film.
I mean, every single scene I got to do with Michael was just the coolest thing ever.
Do you find out who your dad really is?
That’s about all I can say.
I see a potential spin-off here guys!”
Is there a future for you at Showtime?
I’ve done very few things and my two biggest projects have been at Showtime.
Dexter: New Blood,the 10-episode special event series, premieres Nov. 7 on Showtime.