How do you describe a person who delights in prodding your weaknesses. Example: a loan officer of a bank who picks at your plan in a way that is embarrassing and he keeps it up for half an hour.
It can be said that they 'enjoy pushing your buttons'
v. - to push buttons
- To deliberately irritate
- To intentionally provoke another without reason
- To wear away at the patience of someone until that person wants to slap you
- To capitalize on the emotional vulnerabilities of another
I'd go for...
1. Disposed to seek revenge; revengeful.
2. Marked by or resulting from a desire to hurt; spiteful.
Note that etymologically speaking, the first definition above is the "original, true" meaning (from Latin vindicta = vengeance, revenge), but I never hear it used with positive associations (i.e. - exacting justifiable vengeance in response to unjustified bad treatment). And the word is commonly used in the second sense, in contexts where there it simply identifies a person who enjoys causing distress to others, with no implication of "retaliation" (justified or not).
http://www.merriam-webster.com/dictionary/callous I would say callous and indifferent because such people don't have compassion and care for others feelings and are somehow indifferent too.