He is often found in either the Hall of Countenance (where he sleeps from 12 AM until morning) or in The Arcanaeum. He, like Tolfdir, holds and leads lectures, which are held in the Hall of the Elements.
Upon first speaking to Drevis, he will ask the Dragonborn if they can see him, because as he is a Master at Illusion he subsequently thinks he is invisible. Even though he can be seen at all times, the Dragonborn can still choose to say they don't see him.
As part of a miscellaneous side quest, Drevis asks the Dragonborn to wear Mystic Tuning Gloves and help him cleanse many spots around the college. At each spot, the Dragonborn receives several empty Soul Gems of various qualities or an active effect called Fortify Magicka of +25 or +100 for two hours.
"You... You can see me?"
- Of course I can. "Confound it all. I was quite sure I was invisible, or at least transparent."
- I... No, I can't see you. Not at all. "But you can hear me, obviously. Something still isn't quite right. At least I'm making progress."
- Which are the best Illusion spells? "Oh my, that's quite a difficult question. Never underestimate the ability to influence others. Whether they're friends or foes, they're almost all susceptible to Illusion spells. They can turn the tide of a battle in a moment's notice. There are also spells that help in avoiding conflict altogether. Invisibility is tricky to master, but exceptionally useful."
- Out of Balance
Is there any College business I can assist with? "There may be a matter in which your... skills... could be useful. The various points of focus for magic energies around the College have become polluted, and need cleansing. The magical energies underneath the College still require purification. Your assistance would be most useful."
- Why do these "energies" need to be cleansed? "As you may be aware, the College has gone to great lengths to purify and enhance the natural energies of the world. This both enhances our connection to the realm of magic, and eliminates possible interference from outside sources. These energies, on occasion, become... polluted. Effort must be made to see that they are kept pure, clean. Do you wish to aid in this cleansing?"
- All right, I'll help. "Very well. These specially enchanted gloves will allow you to delve directly into the focal points for these energies. Go to each focal point and remove whatever impurities you may find there. Return the gloves to me when you have finished. Please exercise caution. This is not a procedure without possible... consequences."
- What did you need me to do? "Use the gloves to clear the focal points. Return to me when you have finished. I thought I made this rather clear."
- Maybe some other time. "I see."
After cleansing the focal points:
Your focal points have been, uh, cleansed. "Yes, they have. I can feel the difference already. But of course, I'm far more in tune with these sorts of things than most. Thank you. I appreciate your assistance."
- Illusion Ritual Spell
What else is there to be learned about Illusion Magic? "You have gone beyond my teachings, which is quite a feat. I did not think it possible. But there is always more to learn. I believe you are ready for the next step."
- What's the next step? "Knowledge of truly powerful Illusion spells is here at the College, but it is hidden from those who might misuse it. I shall teach you a spell to discern things hidden from others. With it, you will be able to acquire the texts you need. Bring all four to me, and I shall use them to inscribe the spells for you."
After finding the texts:
Here are the texts you requested. "Yes, very good. Here, then, is the first of the Illusion spells you sought."
Drevis Neloren delivers a lecture on Doomstones in the Hall of the Elements; most of the members of the College gather around him to listen to his lecture. After he finishes, everyone goes back to their usual schedule.
"The existence of so-called "Doomstones" throughout Skyrim has been repeatedly verified. The meaning of these stones has not. The prevailing opinion of Skyrim natives is that the stones are indeed magical in nature. While there is no direct evidence of this, it does seem likely."
"References to similar stones appear in lore throughout the various Tamrielic cultures. None, however, exactly match the markings or distribution of Skyrim's stones. At present, there is no confirmation of any of the various theories surrounding the nature of these stones. Their relative positions do not indicate that any individual stone is part of a larger, unobserved pattern. Also, their placement throughout Skyrim does not correspond to any known magical phenomenon."
"The age of the stones themselves has yet to be officially determined. It has been widely assumed that they were placed during the Merethic Era. Writings from that period, including those of Ysgramor himself, do not mention the stones and thus this idea cannot be verified. Nonetheless, many are drawn to these stones based on the local stories describing them as a source of significant power. The College will continue to research these intriguing objects, and of course any findings will be relayed with all possible haste."
- If Nirya is killed, Drevis will say, "Have you seen Nirya? I know she's dead but I thought she'd say hi anyway." The same can happen after Mirabelle Ervine dies.
- Drevis has large amounts of gold on his person and this increases when the Dragonborn trains with him or buys from his shop. It is possible to pickpocket the gold but it can be quite difficult.
- If stolen from, Drevis Neloren will send Hired Thugs after the Dragonborn.
- The Dragonborn has the option to ask Drevis what the best illusion spells, to which he'll reply, "Oh my, that's quite a difficult question. Never underestimate the ability to influence others. Whether they're friends or foes, they're almost all susceptible to Illusion spells. They can turn the tide of a battle in a moment's notice. There are also spells that help in avoiding conflict altogether. Invisibility is tricky to master, but exceptionally useful."
- The Dragonborn is unable to ask the other trainers in the College for their opinions on what are the best spells within their respective schools of magic, making this type of question unique to Drevis only.
- Magicka when equipped. The gloves used during the purification give unlimited
- The buff emitted from the wells after cleansing can grant unlimited magicka for 2 hours. This can be exploited to level very quickly.
- Drevis may occasionally spawn on an unreachable ledge on the side of the mountain underneath the college. Sometimes, it is possible to reach him, by descent to the level of the river, crossing over, and climbing up the hill sides on the right side of the college (facing it). Despite the inconvenience, Drevis can still be interacted with as normal.