Visual clues in the first Irene/Sherlock scene as to their inevitable end— spoilers for “The Woman” and “The Heroine,” Elementary 1x23 and 1x24:
The painting Irene is restoring is a Rubens, The Incredulity of St Thomas: Now Thomas (also known as Didymus), one of the Twelve, was not with the disciples when Jesus came. So the other disciples told him, “We have seen the Lord!” But he said to them, “Unless I see the nail marks in his hands and put my finger where the nails were, and put my hand into his side, I will not believe.” Doubting Thomas was a skeptic, he didn’t believe what he was told— he had to touch Jesus’ wounds before he believed in his resurrection. So we have an obvious resurrection reference here, and we know there will be questions and doubts. Only the wounds can be the proof. Sherlock doesn’t believe things unless he can see them, touch them, know them. So we know Irene is going to die and then miraculously come back, but terribly wounded and in a way that deeply touches and affects Sherlock.
The second painting is Toulouse-Lautrec, La Toillette.
This is an intimate picture, a woman getting out of the bath— another resurrection symbol? And it’s a trusting, vulnerable pose— seated, back turned, half dressed. This is what Irene offers Sherlock: intimacy. This is the temptation she dangles in front of him: run away with me, we’ll be anonymous, faceless. We can wash away the past. We can be clean again, together.
But this model isn’t some imagined ideal. She’s not a wisp or some collection of perfect curves. We can see her bones and joints. She’s solid, she’s real.
(Toulouse-Lautrec often painted prostitutes, so perhaps this is a reference to Irene Adler’s original Arthur Conan Doyle characterization as a fallen/kept woman, or perhaps it echoes Elementary!Sherlock’s penchant for paid company, or his comment in the last episode that Moriarty is a pimp and assassins are his girls.)
Irene is imaginary. She can’t get Sherlock to go away with her, because she isn’t real— she’s a fiction inhabiting Moriarty’s body. When Moriarty gets out of the bath, her naked back betrays her. Sherlock doubts. He touches her, finds the wound where one of the stars in her constellation was removed, and he gets the truth.
Very, very clever, Elementary guys.