Which trustfull and friendly non-player characters do you prefer to "assist" you in completing Boethiah's and Mephala's quests? And weren't you slightly uneasy about finishing these quests?

Cicero from the dark brotherhood is worth killing, depending on how far you are in the campaign.

Lydia was the one I sacraficed to Boethiah.

Then there is Faenal the elf archer from Riverwood. I saw him walk out of my house once. My wife Camilla Valerius was in the bedroom.... enough said.

Really, any follower that is either too hard to reach or you just don't care about, like hirelings, are good for betraying; like the Orc Stronghold followers.

I really wanted some of these people dead, so I didn't really care. Many were equivalent to any other bandit I met.

I only did Boethia's once. I ran to Windhelm, hired that guy in The Candlehearth, and went back. Cost me 500GP, but I had plenty at the time