1. Introduction  
2. XMM-Newton Observations and Data Analysis  
2.1. Imaging Analysis  
2.2. Comparison of the Imaging and Spectral Fluxes  
3. Variability of the Fe Kα Line  
3.1. Comparison of the 2000–2001 and 2012 Scans of the CMZ  
3.2. Multi-Year Variability  
4. Variability in Specific Regions  
4.1. Sgr A: Two Distinct Timescales  
4.2. Sgr B: A Strong Flux Decay and Newly Illuminated Structures  
4.3. Sgr C: Decrease and Displacement  
4.4. Propagation in M359.23–0.04  
4.5. Sgr D: Reflection in a Distant Cloud and Weak Evidence for Variation  
5. Discussion  
5.1. Timescales of Variations  
5.2. Duration of the Illumination in Sgr C  
5.3. Illumination of a 25 pc Long Feature in 10 Years  
6. Conclusions