Here is the review:
-Art-
Another show of improvement. Lines are full now and thicker (in the start they would be gaps between lines sometimes and they were thin). You have a nice variety of poses and expression which is really nice. I am guessing the anatomy is a choice (as in head big and body smaller than the average compare to the head). I believe it work giving the character are not humans giving it it's own unique style.
As for your main concern which was the background I notice you do include more of them such as the police station, interrogation room, etc. I'll use one big example to maybe help you out, it is chapter one - page 28.
This is REALLY, REALLY overabundance of blue, try to find something to break the blue pattern on the wall. Maybe have say a bulletin board in the wall behind one of the characters with it having warnings or other stuff. The point is to have something that makes sense that it should be in the room they are in and helps you break the blue a bit.
Also try not making the floor the same color as the walls, something that happens in your latest chapters (the two being the same colors). Is really rare to find the walls and floor be the same color no matter where you go. If you do, the floor normally has a pattern or something that makes it different than the walls.
-Writing-
I like that you give each character their own form of speaking, giving a nice character to each one. The colored bubbles are also a nice touch helping to know who is saying what in each page. You use good amount of text, not to much but enough to give us all the information we need!
Great coloring on the sound effect to give them that nice extra feeling to them!
-Paneling-
I see is the one page update format, keeping with the standard comic method. I believe it is the best method for one page updates and you are consistent on the space left in between panels. I see that you decide to different the page by making them black (instead of the usual white), is a nice idea, just remember some people associated black black page with it being past events. I doubt they will with yours giving they are all in this pattern
-Story-
I like the concept of the multiverse, though not much has happen to show this (outside of those two falling to one), but the seed is planted and I am sure it'll come up again later on in the story. You have a good pace and are moving the story forward in a good way as it also build up the characters as the story moves (character growth). I look forward to more development and to learn of the situation of the other two lost in the multi-verse!
Keep up the good work and I hope this helps you improve in some aspect.