One of the suggestions we made at the trial of the prototype was that a cycle reservation should automatically reserve you the seat closest to the bike spaces. So in principle, the other cyclist would always be on hand to play Sokoban.
That definitely hasn't percolated as far as the part of the reservation system that Trans Pennine Express inhabits!
A recent** journey I made on one of Trans Pennine Express's "Nova 1" trains (Class 802/3 - effectively the same as Class 800 inside) gave me a bike reservation in coach D and a seat reservation in coach B on both outward and return journeys. So, I sent them a polite message through their customer contact web page asking why, and - more to the point - what they were intending to do to solve this. Most surprisingly, I got a reply!
** 9th May 2022
Dear yorkie,
...
I appreciate you are unhappy with the seat reservation given when a bike reservation has been booked, however, this is an automated process and the system generates seat reservations randomly. I will forward a suggestion on your behalf regarding seats being allocated in Coach D when a bike reservation is booked.
You are able to amend seat reservations via your online account once you have booked. To do this, once you sign into your online account and on the Dashboard page, you can select 'View Bookings' under the Bookings section. This will open a new screen where you will be able to amend a seat reservation. If this does not work, it means there are no seat reservations available for that journey
Your suggestion will be fed back to the relevant manager.
"Seat reservations are generated randomly" is an understatement!
Although it's not as bad as a set of reservations I got on the east coast once: Bike in coach P (Mark 4 Driving Van Trailer), seat at the north end of coach B - the other end of the train, approximately 10 x 23 metre long coaches away!