The king has been killed by a group of assassins.
A lawful evil knight of this king swears to a god that he will avenge his king.
He promises that he will chase them to the end of the world and beyond and he will not rest until all of them have been executed by his own hands.
He is lawful, so he does this because he considers this as his duty as a knight in order to restore law and order.
To which god would such a char make such a promise?
I did not find a god of vengeance on the list of dieties.
In ancient greece it would be nemesis.
background:
I want to make a hexblade/paladin.
But I need a good reason why an evil warlock becomes a paladin.
Here is the story for this char:
Name: Edwin von Unterwald
Race: human
sex: male
class: Hexblade warlock, pact of the blade
alignment: lawful evil
background: noble
Story: Edwin is the son of baron Helmut von Unterwald, who rules over a remote region in the middle of nowhere where you can find nothing but endless dark forests and a few villages. At the age of 16 Edwin was send away to become a knight as it was tradition in his family. He was more than happy to leave this boring place. He went to a temple of Tyr to become a paladin. He had talent, trained harder than most others and had no problem with the lawful part, but he had problems with the good part. He started fights with others, he critisized the trainers for not being strict enough, he insisted on punishing another student for not greeting the instructor properly and he wanted to execute a street kid for stealing some bread from the temple.They kicked him out of the temple, but he got a document that confirms that he has trained there and that he has a talent for combat and magic. He loves documents. He has heared rumors about a cursed area in the forest near his home where even the beasts of the forest did not dare to go. He went there and found an ancient altar. Thanks to his training he performed a ritual to summon whatever was there. A ghosly shadow appeared before him and asked "DO YOU SEEK POWER?" and he ansered YES!!!. The shadow said "THEN PROVE YOURSELF WORTHY" and a giant bear appeared. Edwin killed the bear and offered its blood to the shadow who granted him the power of a warlock in return.
Edwin then went to a large town and asked the king for a job. Working for anyone less then the king himself is beneath him. Several city guards had been killed recently and the king asked him to solve this crime. Edwin found the criminals, forced them to write a confession that they killed the guards, then executed them and gave the king their heads and the confession. The king then made him his agent who is responsible for enforcing order and fighting monsters and criminals.
He was captured by the illithids when they attacked the town, but he managed to escape and he swore to kill all of them and everyone else who is behind those attacks.
- He is obsessed of titles, rules and documents. Anything that is not written down does not exist. He permanently carries the following documents: A document that shows that he carries the title baron and what privileges and duties come with it, a document that he is an agent of the king and what priviledges and duties come with it and the document that proves he has been trained in the temple. He always carries lots of paper and ink and writes down word by word what has been said when he makes a promise, a contract or any business with somebody else. He expects to be paid for his work unless a document says that doing it is part of the duties he already has.
- He is very proud of himself and his titles. Whenever he speaks to others he says: "I am baron Edwin von Unterwald, first enforcer of king XXX. By the power of documet x (e.g. his baron title or an order of the king) I demand that . . ." He always wears an armor with the symbols of his family, his king and his patron. By the way, there is no second enforcer. He chose this title when he started working for the king because it sounds more impressive.
- His patron expects the following things: 1.) In dark and dangerous places he should build a simple shrine for his patron. Do not tell others about the location or what to do there, power needs to be found. 2.) Encourage others to become stronger through facing trials. Power must be earned. Seek challenges and become stronger or die. Maybe the illithids and the toadpole is just another challenge. 3.) Respect power, laws and traditions. Show no mercy for the weak. It is a law of nature that the strong rule the weak. Become stronger and dominate others or live in shame.
- He speaks sylvan very well. He lived in a forest area and farmers are so boring, so the creatures of the forest were the only thing he could talk with. In towns he likes to insult others in that language. It sounds nice and no one understands him.
He had already training in a temple to become a paladin, but he was kicked out because he was lawful but not good.
He searched for another source of power and found his warlock patron.
When this event happens he realizes that he is indeed destenied to become a paladin, he just chose the wrong god the first time.
Maybe the alignment could change to lawful neutral (the duty to serve his king is more importent than his personal gain), but I would prefer if he stays lawful evil. He is definitely lawful and not good.
Prof. Dr. Dr. Mad S. Tist 
