I liked Harry and i'm hoping it's just a blip, but i do have a thing about people banging their hands on a table and poking at a table with their fingers as they talk angrily, it really unsettles me, i think Nicks face said it all as the show finished (the don't poke an angry bear look!).
I can imagine Marc would be very difficult housemate and i don't get Dublin banter
They always say though that what you hate in someone else is a reflection of yourself, so maybe they are clashing because in some ways they are similar.