To Drain a Soul:
1- Find someone who only values one portion of themselves.
For our example, we'll use a person who only likes their mind.
To make sure there is no hidden complacency about appearance, we'll use a woman. Women are your best bet, because they rarely think their looks are sufficient -- but to make even more certain, however, have that woman be past her prime. (If you can find one who's obese, even better…)
Don't forget to check and make sure she's not overly fond of the personality she has to work with, either. You don't want any unwarranted self-esteem getting in the way. Do not exceed an overall neutral perspective. For example, if your subject has truly good friends, be sure that her romantic life has never played out successfully. This will ensure that she feels inadequate and possibly even inept.
2- Beleaguer that which is valued.
The object here is to remove all faith the subject might have in themselves. Set the person up for repeated failures. If you've chosen a subject who values their mind, mess with it. Make them feel stupid and inadequate by ensuring that they are given ONLY tasks they are unfamiliar with and unable to successfully complete in a timely fashion. Surround them with impatient, testy people who question what is taking them so long and why the task wasn't given to someone who knows what they are doing.
Be vigilant, however! Do not let any small triumphs slip in to bolster the subject's courage. They must not be allowed to succeed at anything.
3- Enlist the subject's Inner Critic.
The inner critic is your most valuable ally.
Make sure it is armed with a list of particularly perjorative adjectives to murmur incessantly.
4 - Deprive the person of sleep.
Do not skip this step!
Sleep deprivation is an important part in breaking down a person's defenses. If you cannot create a situation where the subject must physically stay up for long hours, then be sure they get broken, unrestful sleep. Worries, phobias, the inner critic, even loud neighbors and excessive heat… all of these should do the trick.
5- Remove supports.
Effective action here will be dependent on the subject.
You might have a supervisor's child get sick so they are not available for consultation. Perhaps a friend might pass away. Is there someone this person relies on to help them keep their balance? Have that person reach out during a time when the subject is unaware that their phone is off. (This is a two-fer. Not only will the subject be disappointed, but they'll feel stupid, as well. BONUS!) If there's a significant other in the picture, be SURE to have the s/o cancel a much-counted-on date.
6- Keep up the pace.
You don't want to give the subject any time to recover, so be sure to stay on top of the beleaguering. It must be constant and unending.
6a- Watch the calendar!
Whatever you do, don't schedule a drain near any holidays.
Holidays give your subject the time to rest and relax, thus bolstering their defenses.
R&R is the enemy of the soul-drain.