It is interesting to compare the childhood and personality of two.
Both Dieter and Thomas had unhappy childhood, right? Dieter had an abusive father and Thomas was almost abandoned by his adoptive parents. But the results were different-one turned into a monster who took advantage of others and the other became a gentleman who tolerated such monster who fell into his victim. I guess it is an innate personality difference.
Yes, true, anyone who has grown up with trauma copes differently in their lives.
This is an extremely delicate subject and should only be diagnosed by a psychiatrist, but I believe Dieter has some characteristics of narcissistic or antisocial personality disorder. He feels no guilt in deceiving or taking advantage of others(whathe did on SIB and Thomas), has temporary, casual, and frequent relationships, and never hesitated on conducting physical violence(See what he had done on Verona).
And if it is all against Thomas' will, he did several sexual harassment on his business partner.