In Preacher, Denis speaks French twice in season 2 episodes 3 and 4, I feel like maybe if I knew what he was saying I might gain some insight into his character. So what did he say in french?
A Reddit user has provided this translation of Denis' words from S02E03:
it translates roughly to: "It's not Denis, it's Denie. What do you want now? You always want something don't you. Perhaps it's nothing, or it'll be different this time. After you come in to my home, you turn my apartment into a pig sty, you eat and drink like crazy and you party all night. And, where are your other prostitutes? I'm too old for this [...]"
The same user also provided these for S02E04:
"Why all these people in my apartment? You are so selfish. You have been selfish your whole life haven't you? Any why should I endure it?"
Another user has provided these for S02E03 and S02E04:
Episode 3 upon opening the door: "It's not Dennis, it's Denis. What do you want now you always want something eh? It's not going to be different this time. You'll come into my house, turn it into a pigsty, eat all my food and party all night. Where are your other prostitutes? I'm too old for this"
Episode 4: "Why are all these people in my apartment? You are so egotistical, you've been egotistical your whole life huh? Why must I put up with this?"
His first lines to Cassidy and Tulip are;
C'est pas Denis. C'est Denee.
Which translate to "It's not Denis. It's Denee." He is correcting him on the pronunciation of his name.
After Cassidy speaks to him about staying "for a long time", he replies with
All right, come on quick
Meaning he does obviously recognize and know Cassidy, and gives consent for them to stay.
That's it, basically. So far those have been his only lines, beyond grunts.