The one in within which River works with Death. Metaphorically.
- Big Sister Instinct: River grows incredibly protective of her 'siblings' in short time. Being busy for months trying to find her clones and immediately trying to save Tarn and Lily. Her protectiveness over the later goes so far that she kills Lake when he kills Lily and admits that he tricked their other siblings so he would know when his own death was coming.
- Cult: "The Sons and Daughters of the Great Lake" is one, Lake forms a cult around himself after he discovers he can regenerate. His siblings take his ability as a 'blessing' and he tricks them to believe that killing themselves and changing their bodies it's 'ascending to a higher plane.'
- Death Seeker: River's siblings become this after being tricked by Lake that every time they died was a divine ascension.
- Defiant to the End: Rindle. Lake starts using them as a lab rat to count how many regenerations he has on his own. Even after dying four times, they refuse to tell Lake if they regenerated while living away from the others.
- Dramatic Irony: River's speech midway though the story has hints of this. Since the way that she describes her loneliness and her relationship with the Doctor, it's basically how we see her from his perspective. Bonus points for describing him as 'a man who dresses and acts like a ghost'; serving as a subtle foreshadowing from her own nature when she becomes a Data Ghost.
- Family Theme Naming: All River's siblings/clones are named after bodies of water: Lake, Rindle, Wadi, Tarn, Stream, Creek and Beck. Lake's female incarnation, who River names Lily, it's a reference to the water lily.
- Good Is Not Nice: When Lake begs River to not kill him because 'she is better than him', she coldly claims that, yes, a certain kind of person would think that. But she is not one of those people.
- I Cannot Self-Terminate: Terminus Prime is a planet where people can go and choose their own way of dying without real pain since everything it's metaphorical and the clients are just stripped of their life energy. Options go from committing a Heroic Sacrifice, to be eaten by a dragon.
- If You Kill Him, You Will Be Just Like Him: Invoked by Lake when he begs River not to kill him after killing Lily in cold blood and defied by River when she tells him that she is not the kind of people to think like that and kills him.
- I Just Want to Be Loved: The reason why River is looking for the clones. She is tired of being alone and basically the only one of her kind except for her husband who she can't in a linear way.
- Mad Scientist: Lake certainly clarifies, when he discovers he can regenerate, he becomes obsessed with how many lives he has left and starts 'experimenting' to see how long he has left... By murdering his sibling, Rindle. Then, he takes it Up to Eleven when he takes the others to the Terminus Prime facility and convinces them to repeatedly commit suicide so he can count how many regenerations each one has.
- Massive Numbered Siblings: Thanks to Kovarian using River's DNA to make more Time Lords hybrids. Seven clones are showed in this story.
- Resurrection Sickness: As per common with regeneration, River's siblings have it every time they regenerate. Normally cases of Easy Amnesia.
- Stable Time Loop: As per common in River's series, River finds a young woman in the Fantasy Zone (who she later names Lily) and she assumes she is one of her clones/siblings cheated by Lake into wasting her regenerations. It turns out later that she is not and Lake himself doesn't know about her. When Lake kills Lily to test if she has regenerations and sees she doesn't have more left, River kills him and he turns into Lily. Horrified, River realizes that "she was the one that put Lily in the Fantasy Zone" and takes her there to close the loop.
- You Monster!: Said by River to Lake word by word after he confesses deceiving their siblings so they would use up their regenerations and murders Lily in cold blood.