ORS Route Guide: Ian x Alison (Patreon)

Flirt
During Chapter 2, Ian can have lunch with Alison and encourage her by saying "You have everything that's needed to succeed". If he chooses to her at night instead, he needs to tell her "We should do this more often". Later she sends him a selfie and the correct answers are "You're so damn hot"/"You're very beautiful"/"You look good".

When Jeremy ask him what he thinks of Alison, he should answer "She's very hot"

At the bar, Ian must "Go with Alison" then tell her "I liked you too" which allows him to "Kiss her".

If Ian failed or went for Cherry, she ends up with Jeremy but there's still a chance to "Meet Alison" during Chapter 3. During the date, Ian needs to make in clear he's interested "So that's all it takes?" / "I'd say the interest was mutual" and "Kiss Alison".

Date
Not compatible with Alison's Voyeur Route and Emma's Route
During Chapter 5, a scene happens after leaving the club 

During Chapter 6 at The Fortress, Ian can "Bring Alison home right away" but choosing "Yes, you are"/"I like you a lot" is advised.

Love
Not compatible with Lena 's Lover Route and Holly's Route
During Chapter 7, Alison ask Ian to go on a vacation but no matter what he answers he'll be able to go "Go on a trip with Alison" during Chapter 9.

During Chapter 9, Ian and Alison have moment with the fireworks in the background. For the love route, Ian needs to "Embrace her" which allows him to say "I love it too".

Ian x Alison x Jeremy Route (aka Sharing Route)

This is mostly speculation. It might only be a variation of the standard route.

During Chapter 9, right after accepting the trip with Alison, Ian can ask Jeremy "You want to have a threesome?" if their relationship is high enough. Later, Alison will bring it up and Ian can accept by choosing "We could try it".

Jeremy x Alison Route (aka Voyeur Route)

For this alternative route, Alison needs to sleep with Jeremy during Chapter 2.

During Chapter 3, "Tell me the details!".
During Chapter 4, "Show it to me!".
During Chapter 5,  "Show me".
During Chapter 7, "Look at Louise's pictures" then "Ask Jeremy for more pictures".
During Chapter 9, "Play the video".