What was Okabe going to say to Kurisu in the first episode?

Question

I finished the anime and I still wonder what Kurisu said to Okabe in the first episode.

She pulls Okabe out of the conference and says "Back there, you were going to tell me something, weren't you?" and Okabe responds "Back there?". Kurisu says "About fifteen minutes ago" and Okabe says "I don't have the slightest idea".

I guess it has something to do with

time travel and World Line travel in episodes 23 and 24, but unfortunately I didn't watch those episodes that carefully.

However, what did Okabe intend to say to Kurisu, and where, and when?

Answer 1

Around 9 minutes into episode 24 (try watching from 08:30), Okabe from the future (episode 24 Okabe) bumped into Kurisu on the stairs in the radio hall building. He was going to say he would save her, but got interrupted by an announcement over the PA system and ran off.

In episode 1, Kurisu dragged Okabe (episode 1 Okabe) from the lecture, asking what he was going to tell her "about 15 minutes ago". He didn't know as he was episode 1 Okabe and the one she met was episode 24 Okabe.

If you don't understand how that works... Well, that's time travel for you.

Answer 2

Well, if you watch episode 23 when Okabe finds out he kills Kurisu, he screams like a baby just lost its pacifier. Then if you re-watch episode 1, at the beginning just as he's talking to Mayuri about the metal Upa being lost, he hears a scream then goes to check where Kurisu is lying there dead. This is the exact same scream as the one in episode 23.

So, this is the universe where Okabe fails to save her. He mutters as he sees her face again saying "I'm just here to see..." This is where he gets cut off from the voice about Kurisu's father's lecture. So, this is just the Okabe from the future (or present depending on how you look at it) talking to the past or present Kurisu but having a discontinued talk.