The phrase "kept at arm's length" refers to keeping someone at a distance or avoiding close contact with them. Some antonyms for this phrase could include "embraced," "welcomed," "included," or "engaged." These words suggest an opposite approach to interacting with someone, indicating a desire for closeness and involvement. Other antonyms might include "accepted," "trusted," "befriended," or "taken in," all of which imply a willingness to develop a relationship with someone. Overall, these opposite terms reveal a desire for connection and closeness, rather than distance and detachment, which is inherent in the original phrase.