Contents
1. Introduction
2. The Role of X-ray Surveys in Understanding the Nature and the Evolution of SMBHs
2.1. Obscuration as a Challenge to Understand SMBH Growth
2.2. High Angular Resolution X-ray Surveys to Unveil the Elusive Nature of High-z AGN
2.3. The Power of Combining AXIS and JWST Surveys
2.4. SMBH and Host Galaxy Coevolution over Cosmic Time with AXIS
3. AXIS Pillar 1: Determining the Nature of SMBH Seeds with AXIS at  $z=6-10$ XLF
3.1. Accretion Mode and Signatures of the First SMBHs
4. Assembly of Black Holes with Large-Scale Structures as Traced by High-z AGN Clustering
5. AXIS Survey of The First AGN
5.1. The AXIS Wedding Cake Survey
5.2. Synergies
5.3. Stacking Analysis of JWST Detected High-z Galaxies
6. Conclusions