Spoilers ahead then.
Since Chase and Josh are already currently dating (kinda), Joshua will be introducing Pete to Chase bcs Chase wants to know about the child that the guy his dating has ofc. Pete will get into danger with a dog, and even tho Chase is scared of dogs, he chooses to stay with Pete and cover him from the attacking dog.
After this, Joshua asks Chase
"why did you stay and protect Pete even though you're afraid of dogs?"
And Chase will say "it's because he's your child."
"He is your child too" and that's how it's revealed.
What I like about this scene the most is that Chase feels relieved he didn't fuck a dog actually but the first thing he says after knowing he had sex with Joshua during his rut is "did I force you?" And ofc Joshua will say no and they both were consenting.
This is pretty vague but there's your spoilers

omg when he will gonna find out??? someone pls spoil me