There's enough information provided on
Discovery that you can get by showing him just DSC. Once he's hooked, then you can show him the earlier stuff.
The movie that made me a Star Trek fan was
Star Trek IV. I liked it so much, I wanted to see the other movies. Hopefully, after he likes
Discovery, he'll want to see more.
.
.
.
What's the more? I guess...
"In the Mirror Darkly" (ENT). I'm not an ENT Fan, but these are okay, and they show what went on 100 years before the Disco Mirror Universe episodes. "Mirror, Mirror" from TOS too. No need need to go into any Mirror Episodes from DS9. And maybe show him "The Tholian Web" (TOS) so he can see the Space Madness was that Emperor Georgiou was talking about.
Maybe "The Cage" to show him where Pike came from. I don't think you'd need to watch "The Menagerie", unless he
wants to.
For Section 31, I'd show him "Inquisition" and "Inter Arma Enim Silent Leges" from DS9, and that's it.
For the Hell of it, throw in both Harry Mudd episodes from TOS too. "Mudd's Women" and "I, Mudd". If you only want to show him one,
go with "I, Mudd". Bolding intentional. By far, it's the better of the two episodes.
Might as well throw in "Journey to Babel" for Sarek, Amanda, and Spock's relationship with his family.
So, to recap, EDITED LIST (as per suggestions below):
"In the Mirror Darkly" (ENT)
"The Cage" (TOS)
"Mudd's Women" (TOS)
"The Menagerie" (TOS)
"Errand of Mercy" (TOS)
"Amok Time" (TOS)
"Mirror, Mirror" (TOS)
"I, Mudd" (TOS)
"Journey to Babel" (TOS)
"Day of the Dove" (TOS)
"The Tholian Web" (TOS)
"Inquisition" (DS9)
"Inter Arma Enim Silent Leges" (DS9)
If he can't get into '60s TV, that guts most of my list.
Don't show him the two-parter about Klingon Foreheads. You want to get him to
like Star Trek. And all you're doing is confusing the issue on top of it if you show him those. Sometimes, less is more.
