Well, a main theme is the moral ambiguity. In the 'Metal Gear Solid 2 Novel', the actions of the characters are not always clearly right or wrong. For example, some characters may be doing bad things for what they believe is a greater good. Another theme is the relationship between man and machine. The presence of highly advanced war machines like Metal Gears forces the characters to re - evaluate their relationship with technology. Also, the theme of secrecy and revelation plays a part. Secrets are constantly being kept and then revealed, which has a huge impact on the story's progression.
The themes include the exploration of power dynamics. Different factions in the 'Metal Gear Solid 2 Novel' are constantly vying for power, whether it's military power or control over information. There's also the theme of trust. Characters find it difficult to trust each other as they are never sure who is on their side. Additionally, the idea of the future of humanity is a theme. With all the advanced technology like the Metal Gears, the novel makes you think about where humanity is headed in terms of warfare and survival.