Commander Hange,

Once again my apologies for such a tardy reply. I was out of the country and could not contact my volunteers to receive your letter and offer my response in a timely manner. The moment I arrived back home and received your letter, I sat down to write you back.

I must admit that I did not tell you the full story about the lumbar puncture. I did not do this with malicious intent; I simply did not wish to plant expectations into your head and influence your capabilities during an already delicate extraction.

Bertholdt's reaction to his first spinal tap was entirely ordinary. Moreover, only a couple dozen spinal taps were ever carried out during Marley's possession of the intelligent titans, partially out of fear of losing a titan, partially out of a lack of knowledge. Of those couple dozen, only a handful successfully yielded spinal fluid. As such, I had very little resources to guide you, and for this deception, I apologize. I only meant to aid you but was curious how you would report this observation and handle it during your study.

My theory is that the spinal parasite is never meant to be disturbed by outside forces. If it is, then it is because its host is being eaten or in mortal danger. Bertholdt likely wholeheartedly was made to believe by the Colossal Titan parasite that he was being eaten during your test, hence his instinctive desire to flee and his uncharacteristic terror.

My second theory is that this is something he can be trained to withstand. You will both need mental fortitude and courage to continue these spinal taps. Now is when you will need to play into his remorse the most. There will be a time when his fear wins from him; his history may offer him the arguments he needs to press on despite mortal fear. Don't be afraid to reinforce the importance of this research with stronger arguments. Do not coerce him to take tests, but if he refuses, it can be helpful to remind him of why he is there and what he is making up for. The people who were eaten after he breached the wall felt the same fear he does now. This reminder should bridge the period when he is not yet used to the spinal taps.

This is delicate. If he suspects that he is being manipulated into helping out, he may turn away. I trust you possess the diplomatic qualities to avoid giving him that idea. These tests are, after all, a mutually beneficial matter that will allow him to be the hero he hoped to become when he broke the wall.

Now may also be the time to suggest the use of voluntary restraints. Rope and leather straps around his limbs and torso can help keep him still in place, but these need to be primarily a mental crutch. Something to offer him support and to hold onto in times of duress. Do not force this upon him unless he has fully consented to their use well ahead of time. I must stress this because I have seen Marley make this mistake many times, and in each instance, it turned its Warriors against their own motherland just a tad more. This is a precaution against panic, not a solution once it has already occurred. Free him if he loses himself and let him weather out the storm as he needs. He must know he can be let go at any time during the procedure.

Patience and courage, my fellow scientist. We will get past this difficult phase.

It comes as a surprise to me that you lack academic qualifications. You certainly possess academic qualities that many colleges covet. Most doctors and scientists here in Liberio, my father included, were instructed into the trade by their parents. Hands-on experience can be the greatest teacher and keeps us from drifting too far into the purely speculative, theoretical knowledge that robs us of practical application.

Should you be interested, perhaps an erasmus to Liberio might serve you well. The Tybur family founded an Eldian college which offers a wide variety of studies. You get to explore the cultural heritage of your long-lost brethren while you're at it, and we could finally meet in person to exchange knowledge.

I am quite satisfied that you noticed the scientific name for the Colossal Titan. Indeed, like species names, these are ancient Eldian terms to classify the titans, just like we are Homo ymirens and dogs are Canis familiaris.

You already know Titanis colossus. Why don't you try to determine which of these other eight names correspond with which titans?

• Titanis dura

• Titanis mordax

• Titanis armatus

• Titanis reptilis

• Titanis bellua

• Titanis dux

• Titanis chimaera

• Titanis progreditur

My best wishes for your future research. Stay strong, and rely on what makes Bertholdt Bertholdt to coax him into doing the right thing.

Yours truly,

Warchief Zeke Yeager
29th of January, 852