antagonistic

"The school bully was the antagonist in many students' lives. "

"The empty pizza box and crumbs on his face are arguing that my son ate the last slice. "

"None of my siblings are married yet."

"A maverick politician repeatedly interrupted the debate by shouting."

"It is hard work to swim against the current."

"The two students were contending for the highest grade in the class. "

"My brother constantly helps his younger sister with her homework, demonstrating his steadfast loyalty and support. "

"Bob says cats are friendlier than dogs, but I disagree."

"Please direct your attention to the following words."

"The students are competing for the highest grade in the class. "

"He is a student of life."

"Please relate the circumstances of your journey here today."