No one ever expects them.
The Inquisitor is an evil cleric that focuses on healing and debuffs, but also has some impressive damage options available to them as well. They have trouble soloing early on, but they start to get better at it as they grow in level. Generally speaking, it's faster, more enjoyable and more rewarding to spend most of your time in a group as an Inquisitor. They're priests that specialize in single target healing and buffing, being the best evil class for reactive burst healing, although they lack in efficiency compared to the shaman and druid classes. If you do plan to solo, it helps to have the best gear possible for your level, otherwise it is too slow to really make it worth it.
Some of their spells, like Bestowal of Vitae, are reactive heals, enabling the Inquisitor to keep secondary group mates alive while they focus on the tank. Contrite Grace acts similarly on the group, healing when someone is hit a limited number of times before expiring. If you can keep everyone buffed and alive and still have spare time and power, it's a good idea to sling in some damage spells to help the group's overall damage. You won't compare well to a wizard or assassin, but you'll still be bringing targets down faster - and in doing so, reducing the amount of incoming damage that you'll have to heal. Cruel Invocation does some instant divine damage to the target while temporarily silencing them - perfect to use on casting monsters. The responsibility of doing damage on top of main healing isn't an easy thing to do, but your groupmates will recognize your skill when you pull it off effectively. If you find yourself running out of power, however, and losing groupmates as a result, it's a good idea to refocus your efforts on healing, however.
Spells like Digression stun every enemy in an area around the cleric and reduce all threat directed towards them - a life-saving ability that will give your tank time to recover. Incarcerate prevents an enemy from moving for a short period of time, although a hit on them will break the spell.
In most raid environments, Inquisitors will be assigned to healing the main tank and providing buffs for the group. Some of their abilities like Coerced Repentance, which makes it so that whenever the target attacks, its target will counterattack three times, is very useful for building early threat for the tank. The Inquisitor is a challenging and effective healer to play - if you play it right, you won't feel bored. You do a lot more than just watch health bars as an Inquisitor.