There are plenty of options for creating charming characters, but almost none that involve not doing damage.
I'll go on a tangential approach here: Hit points do not equal physical damage. To quote the explanation of Hit Points in the Rules Compendium and the Player's Handbook:
Over the course of a battle, adventurers and monsters take damage from attacks. Hit points measure the ability of a creature to stand up to punishment, turn deadly strikes into glancing blows, and stay on its feet throughout a battle. Hit points represent more than physical endurance. They also represent skill, luck, and resolve—all the factors that combine to help a creature stay alive in combat.
Powers, abilities, and actions that restore hit points are forms of healing. Characters (and some monsters) might regain hit points through rest, heroic resolve, or magic. When a creature heals, add the number of hit points regained to its current hit points. A creature can heal up to its maximum hit point total but can’t exceed it.
You can have an entire fight where the only thing being damaged is someone's resolve to keep on fighting, or their stamina and ability to keep on going. The Fey Warlock's many nightmare-inducing psychic attacks - like Eyebite - very distinctly almost certainly do not inflict any sort of physical harm. Incidentally, this is also why D&D 4e doesn't have a concept of nonlethal damage - because D&D 4e doesn't say that damage is lethal in the first place.
Bearing this in mind, reskin your powers
If your character doesn't physically injure anyone, then what does the damage your character deals represent?
- Does it erode at their willingness to continue fighting?
- Do you have the magical ability to do that, or is that just a mundane result of the force of your personality?
- Do you employ a school of power which aims to weaken people temporarily rather than injure them, sapping their strength and stamina, drawing fights to end through the sides ceasing to fight rather than through someone's death?
For each power that involves harming someone physically, reconsider the flavor text. What other flavor can you apply to that power that has the same mechanical effects?