Flare up and Fire up

Flare up verb - To become very angry.

Fire up and flare up are semantically related in lose one's temper topic. In some cases you can use "Fire up" instead a verb "Flare up".

Fire up verb - To rouse to strong feeling or action.

Flare up and fire up are semantically related in flame topic. Sometimes you can use "Flare up" instead a verb "Fire up", if it concerns topics such as blaze.