The summoned Spectral Assasin Lucien Lachance seems to have something to say about everything.... And hes a good hype man.
Lucien also has the bonus of having his ambient convo. change depending on whether or not you are on a Dark Brotherhood Quest, another Quest, or are just standing around. For instance; when you are on the Brotherhood Quest where you go to the Dawnstar Sanctuary to kill Cicero or let him live, everytime you pause Lucien will have something to say about that Quest.
"This is not the will of the Dread Father. This is not what Sithis wants!" referring to you killing a Dark Brotherhood member who has kept faithful to the Old Ways and the Tenets.
Or when just standing around:
"Maybe we should find some random stranger to kill? Practice does make perfect."
I love Lucien! I'm so glad he got make his cameo!