Motivations | Dimitri's primary motivations change throughout the game. Before the time skip, he's driven by two primary goals. To create a kingdom free from discrimination — where the people from Duscur, especially, could be respected and welcomed — and to locate those responsibility for the tragedy of Duscur and enact revenge upon them. Both of those stem from the same series of incidents, the massacre where his family and friends were killed in front of him and the following near genocide of the Duscur people, done out of misdirected vengeance. Alongside those goals, he also wishes to make other changes to the system, such as the reliance on crests, and to prevent any needless loss of life. Which, as far as he's concerned, is almost any.
After the time skip, specifically post-Chapter 17, he comes to recognize that seeking revenge on behalf of the dead is a destructive path. Instead, he seeks to try and end conflict through acceptance instead of annihilation. His primary motivation from that point on is doing what he feels is best for his people, including his previous goal of creating a society free from discrimination and oppression, along with atoning for the sins he has committed in the past.
Handling Conflict | Oh boy. As long as the conflict does not relate Duscur, anything which may trigger reminders of those incidents, or involve harming innocents, Dimitri is reasonably well equipped to handle issues in a responsible and mature manner. He has a strong sense of duty, a tendency towards fairness, and the willingness to try to appeal to others. He tries to see both sides of a situation, including the problems of society itself, and find solutions which cause the least amount of harm.
That being said, he's far from perfect and has his own blind spots and weaknesses. The most notable is a propensity towards violence and blood lust, particularly in relation to those incidents mentioned above. When confronted with them, he becomes irrational and vicious, unable to listen to reason and generally destructive. Beast like. Those traits range from well-hidden but present, such as before the time skip, to overpowering, which is what we see during and immediately after the time skip. Even once he begins to recover, it still appears briefly when facing those responsible, he's just better at controlling and moving on from those behaviors.
Six Traits | Six primary traits of the character would be compassionate, responsible, self-loathing, sincere, lonely, and driven.
The first is both his greatest strength and worst flaw, as his compassion is what motivates many of his choices — for better or for worse. Dimitri is deeply empathetic and this contributes to both his responsibility and his self-loathing. He takes his duty as a prince with the utmost seriousness and desires to do what is best for all of his people. However, that same urge contributes to his feelings of guilt and fuels his destructive tendencies. In part, because he feels the same consideration towards the dead and therefore must fulfill the revenge they are owed, and in part, because he holds himself to the same moral standards he applies elsewhere. Thus, by his own perspective, his bloodshed and the death he has caused mark him as a monster.
Dimitri is sincere, somewhat painfully so. Though he is capable of masking aspects of his personality, deception does not come to him naturally, and he isn't one to rely on double-meanings. Instead, he tends to be polite and upfront with his feelings. His honest and serious nature can come across as naive and stiff... Which is not always far from the truth.
His loneliness stems from two primary sources. The first is his position within the kingdom, which serves to set him apart from his peers. Though Dimitri himself desires to be seen as an equal and does not believe there's any difference in worth between people, regardless of position, others often feel differently. There are only a few people willing to reach past those borders and treat him accordingly, as a friend. The second reason is his self-loathing. Dimitri often questions whether or not he deserves or is worthy of the care and trust his companions and people show in him.
Finally, driven. Dimitri is always dedicated to giving everything he has for his goals or for those around him. This can be shown in a variety of ways, such as the research he puts into locating the culprit behind Duscur, or his propensity towards overworking himself after reclaiming Fhirdiad. At its worst, this can escalate to full-blown obsession, leading to self-neglect and abandonment of his other goals. This detrimental single-mindedness is best exemplified with his behaviour during and following the time skip.
(He also suffers from frequent hallucinations, specifically of his fallen loved ones demanding he fulfills their revenge, along with headaches, nightmares, and ageusia)