Here is the full list of all 14 ManServant: Gay Visual Novel achievements.
Ask the wrong thing of Pluto
Allow Pluto to choose a punishment
Leave Julian to his fate
A perfect trio
Choose to leave with Karn
It does not pay to offer opinions on former masters
A new vessel, broken
A Happy Ending
A slave in danger
Julian's sacrifice
Silvan and Titan, together forever.
A dangerous attitude
Flee the Capitol
Marius's Beloved