During the events of the The Witcher 3: Wild Hunt Lamberts tells Geralt the story about his friendship with Aiden and his demise by the hands of another witcher of the Cat School, Jad Karadin. Geralt then agrees to help Lambert track down Karadin.
To the surprise of both Wolf School Witchers, upon finding Karadin in Novigrad, he provides another version of the story depicting Aiden in a much less favourable fashion.
Karadin claims that Aiden received payment for a contract yet did not fulfill it. His death was as a matter of fact a tragical accident since Aiden, according to Karadin, lost his temper and was thus shot by the panicking Vienne. However, this version of the story stays vague and can be rebuted due to various reasons.
- ) Lambert worked a considerable amount of time side by side with Aiden, which lends his evaluation of Aiden as a professional witcher the most credibility. According to this, Aiden would have never left a contract unfulfilled or would have tried to cheat his clients.
- ) The sharpshooter Vienne and former member of Karadin´s gang states that the gang´s contracts consisted for a great deal out of killings, making Karadin´s version even more unbelievable.
- ) Lambert has information that Karadin himself dealt the finishing blow to Aiden and not Vienne, like the cat witcher claims. This means that one of the two versions is wrong, since Karadin´s version of events contradicts both Vienne´s and Lambert´s version.
- ) Lambert claims to have solid proof that Karadin, under his new pseudonym, is now active in the slave trade which can be taken as confirmed due to the up-to-dateness of when Lambert gathered this information.
- ) Karadin wrote a letter to Hammond, a former member of the gang, claiming to take no part in the slave trade, however, he mentions other possible traders in Novigrad. Since Karadin almost exlucively took contracts on killings shortly before Aiden died, it raises suspicion how Karadin can possibly know slave traders if he gave up his life as a criminal immediately after the death of Aiden. This implies that Karadin is active in the trade or at least has strong connections to other traders in Novigrad, making his version even less credible.
Due to these facts, it is relatively clear that Karadin´s version is not how the death of Aiden really took place and Lambert´s and Vienne´s information tends to be much more credible. Thus a decision has to be made whether Lambert should follow through with his revenge or whether Karadin should be spared despite the murder of Aiden. It is up to Geralt to decide whether he backs up Lambert in his vengeance or if he wants to take no part in it.
Regardless of the outcome, Aiden is described by Lambert as "the best guy I have ever known". Aiden represents a 1 percent compared to other Cat witchers who show strong sociopathic or psychopathic tendencies, there are still some honourable and professional members left from this school.