How does the director of Se7en establish character?

When we are introduced Morgan freeman's character, somerset, we see that he lives in a bland and incredibly dull apartment, which immediately presents the audience with the representation of Somerset that he may be quite a basic and standard character. Then in the next shot, Somerset is illustrated neatly and very accurately putting on his suit, almost to the point where it appears abnormal to the audience. After we he has put on his suit, we see Somerset picking off a speck of dust off os his suit jacket which is neatly displayed on his bed, which is also incredibly neat and tidy: again to the point where it might appear abnormal to the audience. When Somerset picks off the speck of dust, it becomes a vital part of establishing who he is and what he is like, as it finalises the idea for the audience that he is a very fixed character. After the shots where the audience sees Somerset as a pinpointed character, we see him collect a number of props from a table, which again are neatly arranged. The objects on the table include: a switch-knife, his golden homocide police badge, keys, a pen and a paper rose. Most of the shot supports the constructed idea that Somerset is a focused and undeterred character, except from the paper rose. The rose is angled to the side on the table, and appears to be the first item in Somerset's possession that isn't neatly aligned like everything else. And the paper rose offers no meaning to the audience but clearly holds value to Somerset or it wouldn't be in with his essentials otherwise. Therefore the paper rose is an item that constructs a sense of illusiveness to Somerset, which no other item does in the opening sequence.

When Brad Pitt's character, Mills, is introduced, we see that he is a distracted character and appears to not take the detective role very seriously.Whereas Somerset is very serious and focused on his work unlike Mills. We even see as Somerset and Mills leave the building where they're investigating a murder, that Mills looks at an attractive women as she passes both the characters. This again illustrates the idea that Mills is distracted from his work. From Mills exchanged dialogue with Somerset, we see that he is in some sense a vain character. We see this when Mills interrupts Somerset mid-sentence and from seemingly short answers to some of the questions that Somerset asks, which could suggest that he views himself as superior to Somerset and therefore Somerset is inferior to himself despite Somerset having served in the Homocide department longer than Mills has.