Compassion: What are we afraid of?

Compassion is the wish that the suffering of others be relieved. It's also the wish that the causes of that suffering be dispelled. When learning compassion practices, people sometimes express fear. What are we afraid of? Vulnerability, fear of boundaries dissolving, fear of overwhelm, inadequacy; there are so many places we could find resistance to experiencing direct and intimate contact with our own suffering and the suffering of the world. Is is possible that experiencing compassion will not be what we think? Is it possible it's a step towards freedom?