Breath and The Vast/Lonely vs. Blood and The Buried/Corruption
Breath is concerned with freedom, movement, detachment and apathy. Blood is concerned with unity, attachment, obligation and responsibility.
The Vast is concerned with being in open empty spaces, falling, and insignificance, and The Lonely is concerned with isolation and being alone or disconnected. The Buried is concerned with being crushed and drowned, both literally and figuratively, and The Corruption is concerned with being part of a whole; unhealthy love and companionship.
Breath and The Vast/Lonely
The symbols representing Breath are very similar to the concepts involved in The Vast - wind and flight. Open skies where you can go anywhere you want to, being untethered to the ground. Breath's concepts of indifference and detachment relate to The Vast's realisation that you are a speck within the greatness of the universe - that nothing you do really matters in the grand scheme of things.
Breath is free and disconnected - if The Vast represents the idea of nothing holding you down, The Lonely represents the idea of no one holding you down. The Lonely lets people get away from the responsibility of other people, of being truly free and independent. When you have no one relying on you, or no one to rely on, you can move anywhere and do anything without repercussion. The Lonely is even related to memory loss - becoming free from yourself.
Blood and The Buried/Corruption
Blood's symbols involve metal shackles and chains (representation of being physically bound to something or someone), and The Buried's most prevalent form is the Coffin, which is literally secured in metal chains. Both rely on being weighed down in some way, either by literal dirt or by responsibility and obligation. Those that embrace The Buried find comfort in being held down and compressed; becoming one with the earth. However, responsibility and obligation can be suffocating if you aren't prepared for it.
Blood is related to stability, connection, dependence and attachment. The Corruption has strong ties to being one part of a larger whole, of playing your role within your group (whether that be a swarm, hive or family). It is letting yourself be relied upon and relying on others, because then you're truly loved and wanted. You're needed. Becoming a host for a parasite means you are obligated to stay alive and let yourself be controlled, to be used to further its goals, to help it. Your decaying body is needed as food for fungi and worms and bacteria.
Being Buried and becoming part of the ground and being Corrupted by rot after death both let the cycle of life continue through creating and feeding more life: if you didn't do those things, was your existence as worthwhile as it could have been?
So, to make the Entities work as parallels for the Aspects, four Entities had to pair up. I think Vast & Lonely and Buried & Corruption work quite well together thematically. Being untethered and free from everything versus being obligated and deeply loved by something. Escaping the system or being a core part of the system.