Unbidden and Unforced

Unbidden adjective - Not searched or asked for.

Unforced and unbidden are semantically related in impulsive topic. In some cases you can use "Unforced" instead an adjective "Unbidden", when it comes to topics like agreeable, willing, spontaneous, voluntary.

Unforced adjective - Done, made, or given with one's own free will.

Unbidden and unforced are semantically related in voluntary topic. You can use "Unbidden" instead an adjective "Unforced".