Character chapter transfer.

I am new to the game and have all 3 chapters, but want to start at Prophecies. I want to be an Assassin.

Is there a way to bring that lvl 1 assassin to Prophecies from Factions?

You're out of luck.

You can still do the early missions on an assassin that's able to map travel to Lion's Arch, but most of the quests in the beginning of the game will be unavailable.

Not to mention pre-searing will be completely unavailable.

@OP, I recommend choosing between playing an Assassin and playing Prophecies. While you can be run back near to the start of Prophecies, you'll miss out on all the quests and stuff because those events are considered to take place during the time your Assassin is on Shing Jea Island.

You could always just start a character in both campaigns. That way you'll have Prophecies to learn the game with and Factions for your Assassin. I wouldn't say it's a good solution (I really wouldn't recommend starting in Factions), but it may satisfy you. You may even find yourself really enjoying the profession you start in Prophecies.

Agreed Prophecies had a lot more time put into it for new players to experience all the elements of the game whereas factions was much faster paced as it was geared towards people who already had lvl 20 characters and new the game.

You could start in prophesies and enjoy it right from the beginning, later on take Assassin as a secondary class, that way you can experience all of the prophesies content.
You wouldn't look like an assassin couldnt wear their armour or put points into their primary skill line, but you could use all their skills and weapons.

Starting in Factions as an assassin and later moving to Prophesies puts you part way through that game.
You can however backtrack to ascalon the start city of Prophesies and enjoy all of the map areas and missions.

The start area of prophesies is different to all the other games because there is a devastation in the early part of the game that causes changes in how the map looks.

Read up a little before you decide you have loads of character slots to experiment with classes and can always restart a character.