If you like saving teammates from the brink of death in Apex Legends, Lifeline is the character you want. All of her abilities amp up your ability to heal and revive you're teammates while keeping yourself alive, and they make Lifeline very useful in support roles to back up more aggressive players. Like all the characters in Apex Legends, Lifeline depends on teamwork--she's great at helping out, but it also leaves her vulnerable.
In the original roster of Apex Legends characters, Lifeline is the only one whose designated role is to heal teammates. Her abilities all center on keeping her squad, and herself, alive. Each of the characters in Apex Legends packs three abilities: a passive ability, which happens automatically under certain conditions; an tactical ability you activate with the press of a certain button; and an ultimate ability that charges up over time. For Lifeline, those abilities speed the battle recovery of her team and offer them defensive upgrades.
Lifeline's passive ability allows her to heal herself faster with health items, which is a major boon in the middle of combat. She can also revive teammates much more quickly than other characters, and when she does, she generates a shield in the direction she is facing that protects her and her charge from incoming fire. Her tactical ability drops a health drone that can heal herself and other players over time, allowing you to hold onto your medkits--but be warned, it can also heal enemies who get close enough. Finally, Lifeline can call in care packages with her ultimate ability. They don't include weapons, but they often pack useful defensive upgrades like body shields, helmets, healing items, and weapon attachments.
If you're going with Lifeline, remember that you lack the offensive capabilities of other players like Bangalore or Wraith, which means you might be a little more vulnerable than the other characters on your team. Your most useful ability is reviving other players, so do your best to keep yourself alive and out of harm's way when fighting in battles so that you can help out your squadmates if they go down. And call those care packages like crazy; you can speed up the timer to get more of them with the help of ultimate accelerators.
For more Lifeline tips, check out our complete Lifeline guide and our guide to building effective Apex Legends teams. We've also got guides for all other characters, and tons of pro tips that can help you get ahead.