Rescued hostages will sometimes say 'I knew you would come. Thank you.' in a very sincere voice, which makes a nice change from shrieking clones and burbling corporate cyborgs. Especially heartwarming as the Alert missions sometimes label the Rescue missions as "Abducted Civilian" or "Detained Diplomat Located". Maybe the Tenno aren't as monstrous as they seem.
Evacuating a mission invaded by the Grustrag Three results in the Lotus saying 'The mission was aborted, but you are safe, and that means we won today.' Well, unless she's just worried about losing a valuable resource. Hard to tell really, it's that sort of game.
If the players manage to defeat them, she scolds them for disobeying her—and putting themselves in danger. At the end of the mission, she says she is just happy they're all safe.
The concern in her voice as she tells the players to run away is equal parts Heartwarming and utter Nightmare Fuel because what could possibly scare the Lotus?
If you get captured by the G3, but your team stays to help you instead of getting out of there (when the one that captured you gets killed, you are freed from the cage). Many thankful messages ensue.
Putting yourself in danger to save a downed teammate can easily be this in the right situation.
Or the flip side of this, seeing someone running to save you.
Since Update 14 was released, the Tenno have been able to create domesticated Kubrows (dog-like creatures), take care of them as they grow up, and show them affection to keep their spirits up before bringing them on missions, including petting and scratching them. It really shows there's more to the Tenno than just being deadly space ninjas that kill everything in their path without a second thought; they actually have a soft side.
A meta example- in the wee hours of the morning of June 18, 2014, the devs posted a video of what to expect in the update coming out later that day- an update that had been delayed many weeks by that point, much to many player's annoyance. The general reaction to said video? Concern that the devs looked extremely overworked in the video, and a petition that they all should get some sleep and save working on the update for next week.
In the updated prologue, Lotus pulling all stops to make sure you get off Earth alive. "I can't lose another one" indeed.