てやる

1. 1To do something as a favor for someone of equal or lower status, a close person, an animal or a plant, said casually or bluntly.Ex. 1
2. 2To do something with strong resolve (as in やってやる), or out of spite against another person.

Casual and often masculine-sounding. The favor sense is typically used toward friends, juniors, children or pets. It has the same giving direction as てあげる, from the speaker's side toward someone else, but it is blunter and can sound condescending. The second sense conveys determination or defiance, as in vows and threats, and there need not be any recipient at all.

• てあげるN4「てあげる」 only expresses doing something for someone else; it is more polite and carries a weaker sense of granting a favor than 「てやる」, so it is a better substitute for the first sense in polite contexts. However, the second sense of 「てやる」 (deliberately causing displeasure, or doing something out of spite/determination) cannot be replaced with 「てあげる」.
• てもらうN3「てもらう」 takes the beneficiary as the subject and means receiving someone's help or having someone do something, with the doer marked by 「に」; its register is neutral. 「てやる」 has the giver as the subject, so the perspective is the opposite and the two cannot be swapped. 「てもらう」 also has no spiteful or determined usage.
• てくれるN4「てくれる」 points in the opposite direction: someone does something for me or my side, and the speaker benefits and feels grateful. It can also be used to make requests as 「〜てくれない？」. Its register is neutral, with no nuance of revenge or determination, so the two are not interchangeable.
• 〜ていただくN4「〜ていただく」 takes the beneficiary as the subject and expresses receiving a favor from a superior or elder (the doer marked by 「に」); it is humble and formal, and can also be used for polite requests. 「てやる」 is doing a favor for juniors and the like oneself, so the direction is the opposite and they cannot be swapped.
• なさるN4「てやる」 attaches to the て-form of a verb and means doing something for someone as a favor, or acting out of spite or determination; it is colloquial and condescending. 「なさる」 is the honorific form of 「する」, elevating the actions of elders, customers, and the like, and is formal, so the two cannot be interchanged.
• させてくださいN4「させてください」 is the て-form of the causative plus 「ください」, a polite request for permission to let oneself or one's side do something, with a neutral register. 「てやる」 attaches to the て-form and means doing something for juniors or acting out of spite; it is colloquial and condescending. They cannot be interchanged.

てやる and てあげる both describe doing something for another person, but てやる is rougher, and てくれる marks an action done toward the speaker's side. てもらう and 〜ていただく make the receiver the subject, with 〜ていただく humble, while なさる is an honorific form of する and させてください asks for permission to do something.