Midna, who is barely alive, is delivered to Zelda by Link in his wolf form. Zelda donates her very life to save Midna, who immediately abandons her earlier plans in order to stop Zant and save not just the Twilight Realm, but all of Hyrule. In return, Midna vows to serve and protect Zelda until she dies. Now, this isn't exactly an immortal goddess, but she's going to live forever as long as Zelda does. If Zelda dies, so will Midna. However, there are some theories that say she might be able to be revived through magic...